JP6658551B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery using the same - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte secondary battery using the same.

  With the rapid progress of electronic equipment, the demand for higher capacity of secondary batteries is increasing, and non-aqueous electrolyte batteries such as lithium ion secondary batteries with high energy density are widely used and actively researched. Have been.

In general, an electrolyte used for a non-aqueous electrolyte battery is mainly composed of an electrolyte and a non-aqueous solvent. As the electrolyte of the lithium ion secondary battery, a non-aqueous electrolyte in which an electrolyte such as LiPF ₆ is dissolved in a mixed solvent of a high dielectric constant solvent such as a cyclic carbonate and a low viscosity solvent such as a chain carbonate is used. Have been.

  In a lithium ion secondary battery, when charge and discharge are repeated, the electrolyte is decomposed on the electrode, the material of the battery is deteriorated, and the capacity of the battery is reduced. In some cases, the stability of the battery against swelling or rupture may be reduced.

  Heretofore, there has been proposed a method for improving the battery characteristics of a lithium ion secondary battery by using a specific non-aqueous electrolyte. For example, in Patent Document 1, the use of an electrolytic solution containing maleimide or a derivative thereof suppresses the reaction between lithium metal and the electrolytic solution, and the self-discharge rate when the lithium battery is stored at 60 ° C. for 2 months. Is reported to improve. Patent Document 2 reports that the use of an electrolytic solution containing a compound such as maleimide and vinylene carbonate improves the charge and discharge efficiency of a silicon negative electrode. Patent Document 3 reports that the charge and discharge efficiency of a battery is improved by using a maleimide-based compound and an electrolytic solution containing 0.05% to 5% by weight of a chemical species containing a hydroxyl group having a molecular weight of less than 1000. Have been.

JP-A-11-219723 JP 2009-302058 A JP 2012-174680 A

  The present invention, in a non-aqueous electrolyte secondary battery, suppresses gas generation when the battery is used in a high-temperature environment, improves the remaining capacity of the battery, improves the cycle characteristics, and further has excellent discharge load characteristics. It is another object of the present invention to provide a non-aqueous electrolyte capable of producing a battery (capable of high-rate discharge) and a non-aqueous electrolyte secondary battery using the same.

  Although the inventions described in Patent Literatures 1 to 3 certainly contribute to improvement of some characteristics of the battery, gas generation which is particularly important in the stability of the battery has not been solved at all. It has not been demonstrated that long-term cycle characteristics, which are important in battery characteristics, are improved.

  The present inventor has conducted various studies in order to solve the above problems, and as a result, has found that the above problems can be solved, and has completed the present invention.

That is, the gist of the present invention is:
(1)
A non-aqueous electrolyte used for a secondary battery, comprising a positive electrode having a positive electrode active material capable of occluding and releasing metal ions, and a negative electrode having a negative electrode active material capable of occluding and releasing metal ions. And a non-aqueous electrolyte solution containing a compound represented by the following formula (1).

（式（１）中、Ｒ¹〜Ｒ¹⁶は、それぞれ独立に水素原子、ハロゲン原子、炭化水素基、−Ｏ−Ｌ¹、及び−ＳＯ₂−Ｌ²で表される基のうち、いずれかを表す。Ｌ¹およびＬ²は、炭化水素基を示す。
Ａ¹〜Ａ⁵は、それぞれ独立に、２価の炭化水素基、ヘテロ原子、またはヘテロ原子を有する基を表す。
ｎ¹〜ｎ⁴はそれぞれ０以上の整数を表す。但しｎ¹〜ｎ⁴が全て０である場合、Ｒ³〜Ｒ⁶，Ｒ¹¹〜Ｒ¹⁴のうち少なくとも１つは水素原子以外の基を表す。）
（２）
前記式（１）で表される化合物が、式（２）で表される化合物または式（３）で表される化合物であることを特徴とする（１）に記載の非水系電解液。

(In the formula (1), R ^{1 to} R ¹⁶ are each independently any one of groups represented by a hydrogen atom, a halogen atom, a hydrocarbon group, —OL ¹ , and —SO ₂ —L ² L ¹ and L ² represent a hydrocarbon group.
A ^{1 to} A ⁵ each independently represent a divalent hydrocarbon group, a hetero atom, or a group having a hetero atom.
n ^{1 to} n ⁴ each represent an integer of 0 or more. However, when n ^{1 to} n ⁴ are all 0, at least one of R ^{3 to} R ⁶ and R ^{11 to} R ¹⁴ represents a group other than a hydrogen atom. )
(2)
The non-aqueous electrolyte according to (1), wherein the compound represented by the formula (1) is a compound represented by the formula (2) or a compound represented by the formula (3).

（式（２）中、Ｒ¹⁷〜Ｒ²⁶は、それぞれ独立に水素原子、ハロゲン原子、炭化水素基、−Ｏ−Ｌ¹、及び−ＳＯ₂−Ｌ²で表される基のうち、いずれかを表す。Ｌ¹およびＬ²は、炭化水素基を示す。Ｒ¹⁷〜Ｒ²⁴のうち少なくとも１つは水素原子以外の基を表す。）

(In the formula (2), R ^{17 to} R ²⁶ each independently represent any one of a hydrogen atom, a halogen atom, a hydrocarbon group, —OL ¹ , and a group represented by —SO ₂ —L ² .L ¹ and L ² represents a at least one of the .R ¹⁷ to R ²⁴ that represents a hydrocarbon group represents a group other than a hydrogen atom.)

（式（３）中、Ｒ²⁷〜Ｒ⁴⁴は、それぞれ独立に水素原子、ハロゲン原子、炭化水素基、−Ｏ−Ｌ¹、及び−ＳＯ₂−Ｌ²で表される基のうち、いずれかを表す。Ｌ¹およびＬ²は、炭化水素基を示す。）
（３）
前記式（１）で表される化合物の含有量が、非水系電解液において、０．０１質量％以上５質量％以下であることを特徴とする（１）に記載の非水系電解液。
（４）
前記式（１）で表される化合物において、Ｒ¹〜Ｒ¹⁶が水素原子またはアルキル基であることを特徴とする（１）乃至（３）の何れか一項に記載の非水系電解液。
（５）
非水系電解液中の水分量が質量４０ｐｐｍ以下であることを特徴とする（１）乃至（４）の何れか一項に記載の非水系電解液。
（６）
更に炭素−炭素不飽和結合を有する環状カーボネート及びフッ素原子を有する環状カーボネートのうち、少なくとも一方を含有することを特徴とする（１）乃至（５）の何れか一項に記載の非水系電解液。
（７）
更にニトリル化合物を含有することを特徴とする（１）乃至（６）の何れか一項に記載の非水系電解液。
（８）
金属イオンを吸蔵・放出しうる正極活物質を有する正極と、金属イオンを吸蔵・放出しうる負極活物質を有する負極と、非水系電解液を備える非水系電解液二次電池であって、（１）乃至（７）の何れか一項に記載された非水系電解液を使用することを特徴とする非水系電解液二次電池。

(In the formula (3), R ^{27 to} R ⁴⁴ are each independently any one of a group represented by a hydrogen atom, a halogen atom, a hydrocarbon group, —OL ¹ , and —SO ₂ —L ² .L ¹ and L ² represents a represents a hydrocarbon group.)
(3)
The non-aqueous electrolyte according to (1), wherein the content of the compound represented by the formula (1) is 0.01% by mass or more and 5% by mass or less in the non-aqueous electrolyte.
(4)
The non-aqueous electrolyte according to any one of (1) to (3), wherein in the compound represented by the formula (1), R ^{1 to} R ¹⁶ are a hydrogen atom or an alkyl group.
(5)
The non-aqueous electrolyte according to any one of (1) to (4), wherein the amount of water in the non-aqueous electrolyte is 40 ppm or less by mass.
(6)
The nonaqueous electrolytic solution according to any one of (1) to (5), further comprising at least one of a cyclic carbonate having a carbon-carbon unsaturated bond and a cyclic carbonate having a fluorine atom. .
(7)
The non-aqueous electrolyte according to any one of (1) to (6), further comprising a nitrile compound.
(8)
A non-aqueous electrolyte secondary battery including a positive electrode having a positive electrode active material capable of occluding and releasing metal ions, a negative electrode having a negative electrode active material capable of occluding and releasing metal ions, and a non-aqueous electrolyte solution, A non-aqueous electrolyte secondary battery using the non-aqueous electrolyte described in any one of 1) to (7).

  ADVANTAGE OF THE INVENTION According to this invention, when using a battery in a high temperature environment, it suppresses gas generation, improves the remaining capacity of a battery, improves the cycle characteristics, and further excels in discharge load characteristics (high-rate discharge is possible. ) A non-aqueous electrolyte secondary battery can be obtained.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the following description is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these contents unless it exceeds the gist of the claims.

[1. Non-aqueous electrolyte)
The non-aqueous electrolyte solution of the present invention, like a general non-aqueous electrolyte solution, contains an electrolyte and a non-aqueous solvent that dissolves the electrolyte, and is characterized mainly by containing a bismaleimide compound having a specific structure. .

[1-1. Bismaleimide compound having a specific structure]
Examples of the bismaleimide compound used in the present invention (hereinafter, also referred to as the bismaleimide compound of the present invention) include the following.
1-1-1. Compound represented by formula (1)

（式（１）中、Ｒ¹〜Ｒ¹⁶は、それぞれ独立に水素原子、ハロゲン原子、炭化水素基、−Ｏ−Ｌ¹、及び−ＳＯ₂−Ｌ²で表される基のうち、いずれかを表す。Ｌ¹およびＬ²は、炭化水素基を示す。
Ａ¹〜Ａ⁵は、それぞれ独立に、２価の炭化水素基、ヘテロ原子、またはヘテロ原子を有する基を表す。
ｎ¹〜ｎ⁴はそれぞれ０以上の整数を表す。但しｎ¹〜ｎ⁴が全て０である場合、Ｒ³〜Ｒ⁶，Ｒ¹¹〜Ｒ¹⁴のうち少なくとも１つは水素原子以外の基を表す。）
上記、ハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子が挙げられ、これらの内では電池特性に対する向上効果が大きいため、フッ素原子が最も好ましい。
上記、炭化水素基としては、アルキル基、アルケニル基、アルキニル基、アリール基が挙げられ、これらの内では、反応性が適度で抵抗が低いことからアルキル基が最も好ましい。
炭化水素基の炭素数は、本発明の効果が損なわれない限り特に制限はないが、通常、１以上であり、また通常１０以下、好ましくは５以下、更に好ましくは３以下である。炭素数が多すぎると分子内の立体障害が大きくなりすぎて、電極表面での反応が起きにくくなるためである。
２価の炭化水素基としては、アルキレン基、アルケニレン基、アルキニレン基、フェニレン基が挙げられる。これらの内では、反応性が適度で抵抗が低いことからアルキレン基が最も好ましい。アルキレン基としては、メチレン基、エチレン基、プロピレン基、およびそれらの水素原子の一部または全部がアルキル基に置換された基が挙げられ、これらの内ではメチレン基、メチルメチレン基、ジメチルメチレン基が抵抗が低いことから好ましい。
ヘテロ原子としては、酸素原子、硫黄原子が挙げられ、酸素原子を用いると、正極での反応性が好適となるため好ましい。
ヘテロ原子を有する基としては、−ＳＯ₂−基、−ＣＯ₂−基、−ＯＣＯ₂−基、−Ｏ−ＣＨ₂−基、−ＣＨ₂−Ｏ−ＣＨ₂−基、−ＯＣＨ₂ＣＨ₂Ｏ−基などが挙げられる。これらの中では、−ＳＯ₂−基、−ＣＯ₂−基、−ＯＣＯ₂−基、が負極上での反応性を向上させられるため好ましい。

(In the formula (1), R ^{1 to} R ¹⁶ are each independently any one of groups represented by a hydrogen atom, a halogen atom, a hydrocarbon group, —OL ¹ , and —SO ₂ —L ² L ¹ and L ² represent a hydrocarbon group.
A ^{1 to} A ⁵ each independently represent a divalent hydrocarbon group, a hetero atom, or a group having a hetero atom.
n ^{1 to} n ⁴ each represent an integer of 0 or more. However, when n ^{1 to} n ⁴ are all 0, at least one of R ^{3 to} R ⁶ and R ^{11 to} R ¹⁴ represents a group other than a hydrogen atom. )
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Of these, a fluorine atom is most preferable because of a large effect of improving battery characteristics.
Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group. Among them, an alkyl group is most preferable because of its moderate reactivity and low resistance.
The carbon number of the hydrocarbon group is not particularly limited as long as the effects of the present invention are not impaired, but is usually 1 or more, and usually 10 or less, preferably 5 or less, more preferably 3 or less. This is because if the number of carbon atoms is too large, steric hindrance in the molecule becomes too large, and a reaction on the electrode surface becomes difficult to occur.
Examples of the divalent hydrocarbon group include an alkylene group, an alkenylene group, an alkynylene group, and a phenylene group. Of these, alkylene groups are most preferred because of their moderate reactivity and low resistance. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, and a group in which some or all of the hydrogen atoms have been substituted with an alkyl group. Of these, a methylene group, a methylmethylene group, a dimethylmethylene group Is preferred because of its low resistance.
Examples of the hetero atom include an oxygen atom and a sulfur atom, and the use of an oxygen atom is preferable because reactivity at the positive electrode becomes suitable.
Examples of the group having a hetero atom, -SO ₂ - group, -CO ₂ - group, --OCO ₂ - group, -O-CH ₂ - group, -CH ₂ -O-CH ₂ - group, -OCH ₂ CH ₂ O- group and the like. Among these, a —SO ₂ — group, a —CO ₂ — group, and a —OCO ₂ — group are preferable because reactivity on the negative electrode can be improved.

1-1-2. Compound represented by Formula (2) The bismaleimide compound of the present invention preferably contains Formula (2) described below.

（式中、Ｒ¹⁷〜Ｒ²⁶は、それぞれ独立に水素原子、ハロゲン原子、炭化水素基、−Ｏ−Ｌ¹、及び−ＳＯ₂−Ｌ²で表される基のうち、いずれかを表す。Ｌ¹およびＬ²は、炭化水素基を示す。Ｒ¹⁷〜Ｒ²⁴のうち少なくとも１つは水素原子以外の基を表す。）
上記、ハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子が挙げられ、これらの内では電池特性の向上効果が大きいため、フッ素原子が最も好ましい。
上記、炭化水素基としては、アルキル基、アルケニル基、アルキニル基、アリール基が挙げられ、これらの内では、反応性が適度で抵抗が低いことからアルキル基が最も好ましい。
炭化水素基の炭素数は、本発明の効果が損なわれない限り特に制限はないが、通常、１以上であり、また通常１０以下、好ましくは５以下、更に好ましくは３以下である。炭素数が多すぎると分子内の立体障害が大きくなりすぎて、電極表面での反応が起きにくくなるためである。
Ｒ¹⁷〜Ｒ²⁴が全て水素原子であると、化合物の正極上での反応性が低くなり過ぎ、本発明の効果が小さくなるため、Ｒ¹⁷〜Ｒ²⁴のうち少なくとも１つは水素原子以外の基であることが必要である。正極上での反応性を向上させるため、Ｒ¹⁷〜Ｒ²⁴のうち少なくとも２つは水素原子以外の基であることが好ましく、Ｒ¹⁷〜Ｒ²⁴のうち少なくとも３つは水素原子以外の基であることが更に好ましく、Ｒ¹⁷〜Ｒ²⁴のうち少なくとも４つは水素原子以外の基であることが最も好ましい。
式（２）で表される具体的な化合物としては、以下のものなどが挙げられる。なお、Ｍｅはメチル基を示す。これらの中でも、化合物２−１、化合物２−２、化合物２−８、化合物２−１０、化合物２−１１が正極表面での反応性が適度であるため、本発明の効果を適切に発現できるため好ましい。

(In the formula, R ^{17 to} R ²⁶ each independently represent any of a hydrogen atom, a halogen atom, a hydrocarbon group, —OL ¹ , and a group represented by —SO ₂ —L ² . L ¹ and L ^{2 each} represent a hydrocarbon group, and at least one of R ^{17 to} R ²⁴ represents a group other than a hydrogen atom.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom is most preferable because the effect of improving battery characteristics is large.
Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group. Among them, an alkyl group is most preferable because of its moderate reactivity and low resistance.
The carbon number of the hydrocarbon group is not particularly limited as long as the effects of the present invention are not impaired, but is usually 1 or more, and usually 10 or less, preferably 5 or less, more preferably 3 or less. This is because if the number of carbon atoms is too large, steric hindrance in the molecule becomes too large, and a reaction on the electrode surface becomes difficult to occur.
When all of R ^{17 to} R ²⁴ are hydrogen atoms, the reactivity of the compound on the positive electrode becomes too low, and the effect of the present invention is reduced. Therefore, at least one of R ^{17 to} R ²⁴ is other than a hydrogen atom. Group. To improve the reactivity of the positive electrode, it is preferable that at least two of R ¹⁷ to R ²⁴ is a group other than a hydrogen atom, at least three non-hydrogen atom group of R ¹⁷ to R ²⁴ More preferably, at least four of R ^{17 to} R ²⁴ are most preferably a group other than a hydrogen atom.
Specific examples of the compound represented by the formula (2) include the following. Me represents a methyl group. Among them, Compound 2-1, Compound 2-2, Compound 2-8, Compound 2-10, and Compound 2-11 have appropriate reactivity on the positive electrode surface, so that the effects of the present invention can be appropriately exhibited. Therefore, it is preferable.

1-1-3. Compound represented by Formula (3) The bismaleimide compound of the present invention preferably contains at least one compound represented by Formula (3) described below.

（式中、Ｒ²⁷〜Ｒ⁴⁴は、それぞれ独立に水素原子、ハロゲン原子、炭化水素基、−Ｏ−Ｌ¹、及び−ＳＯ₂−Ｌ²で表される基のうち、いずれかを表す。Ｌ¹およびＬ²は、炭化水素基を示す。）
上記、ハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子が挙げられ、これらの内では電池特性に対する向上効果が大きいため、フッ素原子が最も好ましい。
上記、炭化水素基としては、アルキル基、アルケニル基、アルキニル基、アリール基が挙げられ、これらの内では、反応性が適度で抵抗が低いことからアルキル基が最も好ましい。
炭化水素基の炭素数は、本発明の効果が損なわれない限り特に制限はないが、通常、１以上であり、また通常１０以下、好ましくは５以下、更に好ましくは３以下である。炭素数が多すぎると分子内の立体障害が大きくなりすぎて、電極表面での反応が起きにくくなるためである。
アルキル基の具体例としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔ−ブチル基、ｔ−アミル基などが挙げられる。アルケニル基の例としては、ビニル基、アリル基、１−プロペニル基、１−ブテニル基などが挙げられる。アルキニル基の例としては、エチニル基、プロピニル基などが挙げられる。アリール基の例としては、フェニル基、２−トリル基、３−トリル基、４−トリル基、ベンジル基、４−t−ブチルフェニル基、４−ｔ−アミルフェニル基などが挙げられる。これらの内では、メチル基、エチル基、プロピル基、イソプロピル基、ｔ−ブチル基、ｔ−アミル基が好ましく、特にメチル基、エチル基、プロピル基が、反応性が適度で抵抗が低いことから好ましい。
式（３）で示される具体的な化合物としては、以下のものなどが挙げられる。これらの中でも、化合物３−２が正極表面での反応性が適度であるため、本発明の効果を適切に発現できるため好ましい。

(In the formula, R ^{27 to} R ⁴⁴ each independently represent any one of a hydrogen atom, a halogen atom, a hydrocarbon group, —OL ¹ , and a group represented by —SO ₂ —L ² . L ¹ and L ² represent a hydrocarbon group.)
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Of these, a fluorine atom is most preferable because of a large effect of improving battery characteristics.
Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group. Among them, an alkyl group is most preferable because of its moderate reactivity and low resistance.
The carbon number of the hydrocarbon group is not particularly limited as long as the effects of the present invention are not impaired, but is usually 1 or more, and usually 10 or less, preferably 5 or less, more preferably 3 or less. This is because if the number of carbon atoms is too large, steric hindrance in the molecule becomes too large, and a reaction on the electrode surface becomes difficult to occur.
Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, and a t-amyl group. Examples of the alkenyl group include a vinyl group, an allyl group, a 1-propenyl group, a 1-butenyl group and the like. Examples of the alkynyl group include an ethynyl group and a propynyl group. Examples of the aryl group include a phenyl group, a 2-tolyl group, a 3-tolyl group, a 4-tolyl group, a benzyl group, a 4-t-butylphenyl group and a 4-t-amylphenyl group. Of these, a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, and a t-amyl group are preferable. Particularly, a methyl group, an ethyl group, and a propyl group have moderate reactivity and low resistance. preferable.
Specific examples of the compound represented by the formula (3) include the following. Among them, the compound 3-2 is preferable since the reactivity on the positive electrode surface is appropriate and the effects of the present invention can be appropriately exhibited.

上記の化合物を用いると、負極の表面に均一な被膜を形成することにより、高温時の容量低下を抑制し、さらに正極表面上でも反応可能であるため、サイクル特性を向上させる効果が大きい。これらは単独で用いても、２種類以上を併用してもよい。
上記の化合物の中でも電極上を広く保護できる被膜を形成するためのため、式３−２の化合物及び式３−３の化合物が好ましく、特に式３−２の化合物が好ましい。
上記の化合物を用いるときは非水系電解液中に、０．０１質量％以上含有することが好ましく、０．０３質量％以上含有することが更に好ましく、０．０５質量％以上含有することが最も好ましい。また、５質量％以下の含有量で用いることが好ましく、３質量％以下の含有量で用いることがさらに好ましく、１．５質量％以下の含有量で用いることが特に好ましく、０．８質量％以下の含有量で用いることが最も好ましい。上記の含有量で用いることで、高温保存特性、サイクル特性の向上効果を十分に得ることができると共に、不要な抵抗上昇を抑制することができる。
上記の化合物を用いることで、高温状態でのガス発生や残存容量の低下を抑制し、さらには長期間のサイクル特性を向上することができるが、その理由はいまだ明らかになっていない。しかし、以下の様にその効果からメカニズムを推察することができる。本発明では、上記のような特定の構造を有するビスマレイミド化合物を用いているが、その構造上の特徴はベンゼン環を有し、かつ置換基を有するか、ヘテロ元素を有する基を含むことにあり、通常のビスマレイミドよりも正極に対し酸化電位が低くなり、その結果正極活物質状上での反応性が上昇していると考えられる。その為、負極上に被膜を形成するだけでなく、正極上に保護被膜を形成する能力が高く、上記のような特性向上効果が得られるものと推察している。

When the above compound is used, a uniform film is formed on the surface of the negative electrode to suppress a decrease in capacity at a high temperature, and the compound can react even on the surface of the positive electrode. Therefore, the effect of improving the cycle characteristics is large. These may be used alone or in combination of two or more.
Of the above compounds, a compound of the formula 3-2 and a compound of the formula 3-3 are preferable, and a compound of the formula 3-2 is particularly preferable, in order to form a film capable of widely protecting the electrode.
When the above compound is used, the content is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, most preferably 0.05% by mass or more in the non-aqueous electrolyte solution. preferable. Further, it is preferably used at a content of 5% by mass or less, more preferably at a content of 3% by mass or less, particularly preferably at a content of 1.5% by mass or less, and more preferably 0.8% by mass. It is most preferable to use the following content. By using the above content, the effect of improving the high-temperature storage characteristics and the cycle characteristics can be sufficiently obtained, and an unnecessary increase in resistance can be suppressed.
By using the above compound, it is possible to suppress the generation of gas and the decrease in the remaining capacity in a high temperature state, and further to improve the long-term cycle characteristics, but the reason has not been elucidated yet. However, the mechanism can be inferred from the effects as follows. In the present invention, a bismaleimide compound having a specific structure as described above is used, and its structural feature is that it has a benzene ring and has a substituent or a group having a hetero element. It is considered that the oxidation potential is lower than that of normal bismaleimide with respect to the positive electrode, and as a result, the reactivity on the positive electrode active material is increased. Therefore, it is presumed that not only the ability to form a film on the negative electrode but also the ability to form a protective film on the positive electrode is high, and that the above-described effect of improving characteristics can be obtained.

[1-2. Moisture content in electrolyte)
The amount of water in the non-aqueous electrolyte is not particularly limited, but is preferably 50 ppm by mass or less, more preferably 40 ppm by mass or less, and particularly preferably 30 ppm by mass or less. Further, it is preferably at least 1 mass ppm, more preferably at least 2 mass ppm, particularly preferably at least 3 mass ppm. Within the above range, the generation of acid in the electrolytic solution is suppressed, and the steps in the production of the electrolytic solution can be relatively simplified.

[1-3. Other compounds)
Compounds that may be used in combination with a bismaleimide compound having a specific structure include a cyclic carbonate having a carbon-carbon double bond, a carbonate having a halogen atom, a nitrile compound, a compound having an SＳO bond, and a compound having an isocyanate group. , A compound represented by the formula (X), a difluorophosphate, and a dicarboxylic acid ester.

[1-3-1. Cyclic carbonate having a carbon-carbon double bond)
Examples of the cyclic carbonate having a carbon-carbon double bond include, for example, vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 1,2-dimethylvinylene carbonate, 1,2-diethylvinylene carbonate, fluorovinylene carbonate, and trifluoromethylvinylene. Vinylene carbonate compounds such as carbonates; vinylethylene carbonate, 1-methyl-2-vinylethylene carbonate, 1-ethyl-2-vinylethylene carbonate, 1-n-propyl-2-vinylethylene carbonate, 1-methyl-2- Vinyl ethylene carbonate compounds such as vinyl ethylene carbonate, 1,1-divinyl ethylene carbonate, 1,2-divinyl ethylene carbonate; 1,1-dimethyl-2-methylene Methylene ethylene carbonate compounds such as ethylene carbonate and 1,1-diethyl-2-methylene ethylene carbonate. These may be used alone or in combination of two or more.

  When a cyclic carbonate compound having a carbon-carbon double bond is contained, the content in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass. %, Usually 10% by mass or less, preferably 8% by mass or less, more preferably 6% by mass or less. When the content of the cyclic carbonate compound having a carbon-carbon double bond is within the above range, not only cycle characteristics are improved, but also gas characteristics can be particularly improved, such as gas generation can be suppressed and internal resistance can be reduced. preferable.

[1-3-2. A carbonate having a halogen atom)
The carbonate having a halogen atom is not particularly limited, and examples thereof include the following.
Examples of the halogen atom of the carbonate having a halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and among these, a fluorine atom and a chlorine atom are preferable, and a fluorine atom is particularly preferable.
As the carbonate having a fluorine atom, a chain carbonate having a fluorine atom, a cyclic carbonate having a fluorine atom is preferable, and as the chain carbonate having a fluorine atom, for example, fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl Carbonate, trifluoroethyl methyl carbonate, bis (trifluoroethyl) carbonate and the like. Above all, trifluoroethyl methyl carbonate and bis (trifluoroethyl) carbonate are preferable because a stable film is easily formed and the stability of the compound is high.
Examples of the cyclic carbonate having a fluorine atom include fluorinated cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. For example, fluorinated ethylene carbonate (hereinafter, referred to as “fluorinated ethylene carbonate” May be described), and derivatives thereof. Examples of the derivative of the fluorinated ethylene carbonate include a fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Among them, fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof are preferable.

  Examples of the fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene Carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethyl Le ethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

  Among them, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferable because they impart high ionic conductivity to the electrolytic solution and easily form a stable interfacial protective film. These may be used alone or in combination of two or more.

  The content of the carbonate having a halogen atom is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.5% by mass or more. Further, it is preferably used at a content of 15% by mass or less, more preferably at a content of 10% by mass or less, and most preferably at a content of 7% by mass or less. By using the above content, the effect of improving high-temperature storage characteristics and cycle characteristics can be sufficiently obtained, and unnecessary gas generation can be suppressed.

[1-3-3. Nitrile compound)
The nitrile compound is not particularly limited, but examples include the following.
As the nitrile compound, for example,
Acetonitrile, propionitrile, butyronitrile, valeronitrile, hexanenitrile, heptanenitrile, octanenitrile, nonanenitrile, decanenitrile, lauronitrile, tridecanenitrile, tetradecanenitrile, hexadecanenitrile, pentadecanenitrile, heptadecanonitrile, heptadecanonitrile Decannitrile, icosannitrile, crotononitrile, methacrylonitrile, acrylonitrile, methoxyacrylonitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azelanitrile, sebaconitrile, debaconitrile, sebaconitrile Nitrile, ethylmalononitrile, isopropylmalononitrile, t rt-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethyl Succinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile, bicyclohexyl-2, 2-dicarbonitrile, bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2 -Diisobutyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile , 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaro Nitrile, 2,3,3,4-tetramethylglutaronitrile, maleonitrile, fumaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6 -Dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3 ′-(ethylenedioxy) dipropionitrile, 3,3 ′-(ethylenedithio) dipro Pionitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane.

  Of these, mononitrile, dinitrile, trinitrile, and tetranitrile are preferred from the viewpoint of handling. If the number of nitriles is too large, the toxicity of the compound increases. The carbon number of the mononitrile is usually 2 or more, preferably 3 or more, more preferably 4 or more, while it is usually 20 or less, preferably 18 or less, more preferably 11 or less. The carbon number of dinitrile is usually 3 or more, preferably 4 or more, more preferably 5 or more, while it is usually 20 or less, preferably 10 or less, more preferably 8 or less. The carbon number of trinitrile is usually 4 or more, preferably 5 or more, more preferably 6 or more, while it is usually 20 or less, preferably 18 or less, more preferably 11 or less. The carbon number of tetranitrile is usually 5 or more, preferably 6 or more, more preferably 7 or more, while it is usually 20 or less, preferably 18 or less, more preferably 11 or less. In this range, the effect of protecting the electrode is large and the increase in viscosity can be suppressed.

  Of these, valeronitrile, octanenitrile, lauronitrile, tridecanenitrile, tetradecanenitrile, hexadecanenitrile, pentadecanenitrile, heptadecanenitrile, octadecanenitrile, nonadecanenitrile, crotononitrile, acrylonitrile, methoxyacrylonitrile, malonoxynitrile Nitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, azeranitrile, sebaconitrile, undecandinitrile, dodecandinitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5 Undecane and fumaronitrile are preferred from the viewpoint of improving storage characteristics. Further, valeronitrile, octanenitrile, lauronitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, glutaronitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxa Spiro [5,5] undecane is more preferable because it has a particularly excellent effect of improving storage characteristics and has little deterioration due to side reactions at the electrode. In general, as the molecular weight of the nitrile compound decreases, the proportion of cyano groups in one molecule increases, and the viscosity of the molecule increases. On the other hand, the boiling point of the compound increases as the molecular weight increases. Accordingly, valeronitrile, octanenitrile, lauronitrile, succinonitrile, adiponitrile, and pimeronitrile are more preferable from the viewpoint of improving work efficiency. These may be used alone or in combination of two or more.

  The content of the nitrile compound is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.5% by mass or more. Further, it is preferably used at a content of 6% by mass or less, more preferably at a content of 5% by mass or less, most preferably at 4% by mass or less. By using the above content, the effect of improving the high-temperature storage characteristics and the cycle characteristics can be sufficiently obtained, and an unnecessary increase in resistance can be suppressed.

[1-3-4. Compound having S = O bond]
The compound having an S ＝ O bond is not particularly limited, but examples include the following.
Examples of the compound having an S ＝ O bond include a chain sulfonic acid ester, a cyclic sulfonate ester, a chain sulfate ester, a cyclic sulfate ester, a chain sulfite ester, a cyclic sulfite ester, a chain sulfone, a cyclic sulfone, and the like. Can be Among them, it is preferable to use a chain sulfonic acid ester, a cyclic sulfonic acid ester, a chain sulfate ester, or a cyclic sulfate ester, since the effect of improving cycle characteristics is large.
Examples of the chain sulfonic acid ester include the following.
Fluorosulfonic acid esters such as methyl fluorosulfonic acid and ethyl fluorosulfonic acid;
Methyl methanesulfonate, ethyl methanesulfonate, 2-propynyl methanesulfonate, 3-butynyl methanesulfonate, busulfan, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2- 2-propynyl (methanesulfonyloxy) propionate, 3-butynyl 2- (methanesulfonyloxy) propionate, methyl methanesulfonyloxyacetate, ethyl methanesulfonyloxyacetate, 2-propynyl methanesulfonyloxyacetate and 3-methanesulfonyloxyacetate Methanesulfonic acid esters such as butynyl;
Methyl vinyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl allyl sulfonate, propargyl allyl sulfonate and 1,2-bis (vinyl sulfonyloxy ) Alkenylsulfonic acid esters such as ethane;
Methoxycarbonylmethyl methanedisulfonic acid, ethoxycarbonylmethyl methanedisulfonic acid, 1-methoxycarbonylethyl methanedisulfonic acid, 1-ethoxycarbonylethyl methanedisulfonic acid, methoxycarbonylmethyl 1,2-ethanedisulfonic acid, 1,2-ethanedisulfonic acid Ethoxycarbonylmethyl, 1-methoxycarbonylethyl 1,2-ethanedisulfonic acid, 1-ethoxycarbonylethyl 1,2-ethanedisulfonic acid, methoxycarbonylmethyl 1,3-propanedisulfonic acid, ethoxycarbonyl 1,3-propanedisulfonic acid Methyl, 1-methoxycarbonylethyl 1,3-propanedisulfonic acid, 1-ethoxycarbonylethyl 1,3-propanedisulfonic acid, methoxycarbonyl 1,3-butanedisulfonic acid Methyl, 1,3-butane disulfonic acid ethoxycarbonylmethyl, 1,3-butane disulfonic acid 1-methoxycarbonyl-ethyl, alkyl disulfonic acid esters, such as 1,3-butane disulfonic acid 1-ethoxycarbonylethyl.
Examples of the cyclic sulfonate include the following.
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone , 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene -1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2 -Fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2-methyl-1-prope -1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3 Sultone compounds such as -methyl-2-propene-1,3-sultone, 1,4-butanesultone and 1,5-pentanesultone;
Disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate.
Examples of the chain sulfate include the following.
Dialkyl sulfate compounds such as dimethyl sulfate, ethyl methyl sulfate and diethyl sulfate.
Examples of the cyclic sulfate include the following.
1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate, 1,3-butylene sulfate, 1,4-butylene sulfate, 1, Alkylene sulfate compounds such as 2-pentylene sulfate, 1,3-pentylene sulfate, 1,4-pentylene sulfate and 1,5-pentylene sulfate.
Examples of the chain sulfite include the following.
Dialkyl sulfite compounds such as dimethyl sulfite, ethyl methyl sulfite and diethyl sulfite.
Examples of the cyclic sulfite include the following.
1,2-ethylene sulfite, 1,2-propylene sulfite, 1,3-propylene sulfite, 1,2-butylene sulfite, 1,3-butylene sulfite, 1,4-butylene sulfite, 1, Alkylene sulfite compounds such as 2-pentylene sulfite, 1,3-pentylene sulfite, 1,4-pentylene sulfite, and 1,5-pentylene sulfite.
Examples of the chain sulfone include the following.
Dialkyl sulfone compounds such as dimethyl sulfone and diethyl sulfone.
Examples of the cyclic sulfone include the following.
Alkylene sulfone compounds such as sulfolane, methyl sulfolane and 4,5-dimethyl sulfolane, and alkynylene sulfone compounds such as sulfolene;
Of these, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2-propynyl 2- (methanesulfonyloxy) propionate, 1-methoxycarbonylethyl propanedisulfonate, propanedisulfone 1-ethoxycarbonylethyl acid, 1-methoxycarbonylethyl butanedisulfonic acid, 1-ethoxycarbonylethyl butanedisulfonic acid, 1,3-propanesultone, 1-propene-1,3-sultone, 1,4-butanesultone, 1, 2-Ethylene sulfate, 1,2-ethylene sulfite, methyl methanesulfonate and ethyl methanesulfonate are preferred from the viewpoint of improving storage characteristics, and 1-methoxycarbonylethyl propanedisulfonic acid and 1-e-propanedisulfonic acid are preferred. Xycarbonylethyl, 1-methoxycarbonylethyl butanedisulfonic acid, 1-ethoxycarbonylethyl butanedisulfonic acid, 1,3-propanesultone, 1-propene-1,3-sultone, 1,2-ethylenesulfate, 1,2 -Ethylene sulfite is more preferred, and 1,3-propane sultone and 1-propene-1,3-sultone are still more preferred. These may be used alone or in combination of two or more.

  The content of the compound having an S ＝ O bond is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.5% by mass or more. Further, it is preferably used in a content of 5% by mass or less, more preferably in a content of 4% by mass or less, and most preferably in a content of 3% by mass or less. By using the above content, the effect of improving the high-temperature storage characteristics and the cycle characteristics can be sufficiently obtained, and the unnecessary increase in resistance can be suppressed.

[1-3-5. Compound having isocyanato group (N = C = O group)]
The compound having an isocyanato group (N = C = O group) is not particularly limited, but examples include the following.
Examples of the organic compound having an isocyanate group include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, tert-butyl isocyanate, pentyl isocyanate hexyl isocyanate, cyclohexyl isocyanate, vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, propargyl isocyanate, and phenyl Organic compounds having one isocyanate group such as isocyanate and fluorophenyl isocyanate;

Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-diisocyanate Natopropane, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5 Diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6 Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanato Methyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1 ′ Diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, bicyclo [2.2.1] heptane-2, 5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, Organic compounds having two isocyanate groups such as 1,5-diisocyanatopentane-1,5-dione, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate ;
And the like.

  Among them, monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane- 2,6-diylbis (methyl isocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethyle Organic compounds having two isocyanate groups, such as diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate, are preferred from the viewpoint of improving storage characteristics. Hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane , Dicyclohexylmethane-4,4'-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate) , Isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate are more preferred, and 1,3-bis (isocyanatomethyl) cyclohexane and dicyclohexylmethane-4 are preferred. , 4'-diisosi Sulfonates, bicyclo [2.2.1] heptane-2,5-diyl bis (methyl isocyanate), bicyclo [2.2.1] heptane-2,6-diyl bis (methyl isocyanate) are more preferred. These may be used alone or in combination of two or more.

  The content of the compound having an isocyanato group (N = C = O group) in the non-aqueous electrolyte is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.2% by mass or more. preferable. Further, it is preferably used in a content of 5% by mass or less, more preferably in a content of 3% by mass or less, and most preferably in a content of 2% by mass or less. By using the content in the above range, the effect of improving the high-temperature storage characteristics and the cycle characteristics can be sufficiently obtained, and an unnecessary increase in resistance can be suppressed.

[1-3-6. Compound represented by formula (X)]

（Ｒ⁴⁵、Ｒ⁴⁶、Ｒ⁴⁷は、それぞれ独立にハロゲン原子、シアノ基、エステル基、エーテル基を有しても良い有機基を表す。）
Ｒ⁴⁵、Ｒ⁴⁶、Ｒ⁴⁷が表すハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子が挙げられ、これらの内では電池特性に対する向上効果が大きいため、フッ素原子が最も好ましい。ハロゲン原子、シアノ基、エステル基、エーテル基を有しても良い有機基としてはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔ−ブチル基、ｔ−アミル基、ビニル基、アリル基、１−プロペニル基、１−ブテニル基、エチニル基、プロピニル基、フェニル基、２−トリル基、３−トリル基、４−トリル基、ベンジル基、４−t−ブチルフェニル基、４−ｔ−アミルフェニル基などの炭化水素基、フルオロメチル基、トリフルオロメチル基、トリフルオロエチル基などのフッ素化炭化水素基、シアノメチル基、シアノエチル基、シアノプロピル基、シアノブチル基、シアノペンチル基、シアノヘキシル基などのシアノ炭化水素基、エトキシカルボニル基、エトキシカルボニルメチル基、１−エトキシカルボニルエチル基、アセトキシ基、アセトキシメチル基、１−アセトキシエチル基、アクリロイル基、アクリロイルメチル基、１−アクリロイルエチル基などのエステル基を有する有機基、メトキシ基、エトキシ基、メトキシメチル基、エトキシメチル基、メトキシエチル基、エトキシエチル基などのエチル基を有する有機基などが挙げられる。
式（Ｘ）で表される化合物としては特に限定されないが、例えば以下のものが挙げられる。
トリビニルイソシアヌレート、トリ（１−プロペニル）イソシアヌレート、トリアリルイソシアヌレート、トリメタリルイソシアヌレート、メチルジアリルイソシアヌレート、エチルジアリルイソシアヌレート、ジエチルアリルイソシアヌレート、ジエチルビニルイソシアヌレート、トリ（プロパルギル）イソシアヌレート、トリス（２−アクリロキシメチル）イソシアヌレート、トリス（２−アクリロキシエチル）イソシアヌレート、トリス（２−メタクリロキシメチル）イソシアヌレート、トリス（２−メタクリロキシエチル）イソシアヌレート、ε−カプロラクトン変性トリス−（２−アクリロキシエチル）イソシアヌレートが挙げられ、中でもトリアリルイソシアヌレート、トリメタリルイソシアヌレート、トリス（２−アクリロキシエチル）イソシアヌレート、トリス（２−メタクリロキシエチル）イソシアヌレート、ε−カプロラクトン変性トリス−（２−アクリロキシエチル）イソシアヌレートが好ましく、トリアリルイソシアヌレート、トリス（２−アクリロキシエチル）イソシアヌレートはサイクル特性の向上効果が大きいため特に好ましい。これらは単独で用いても、２種類以上を併用してもよい。

(R ⁴⁵ , R ⁴⁶ and R ⁴⁷ each independently represent a halogen atom, a cyano group, an ester group, or an organic group which may have an ether group.)
Examples of the halogen atom represented by R ⁴⁵ , R ⁴⁶ , and R ⁴⁷ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Of these, a fluorine atom is most preferable because of a large effect of improving battery characteristics. Examples of the organic group which may have a halogen atom, a cyano group, an ester group, or an ether group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a t-amyl group, and vinyl. Group, allyl group, 1-propenyl group, 1-butenyl group, ethynyl group, propynyl group, phenyl group, 2-tolyl group, 3-tolyl group, 4-tolyl group, benzyl group, 4-t-butylphenyl group, Hydrocarbon groups such as 4-t-amylphenyl group, fluorinated hydrocarbon groups such as fluoromethyl group, trifluoromethyl group and trifluoroethyl group, cyanomethyl group, cyanoethyl group, cyanopropyl group, cyanobutyl group, cyanopentyl group , A cyanohydrocarbon group such as a cyanohexyl group, an ethoxycarbonyl group, an ethoxycarbonylmethyl group, a 1-ethoxycarbonyl group. Organic group having an ester group such as ethyl group, acetoxy group, acetoxymethyl group, 1-acetoxyethyl group, acryloyl group, acryloylmethyl group, 1-acryloylethyl group, methoxy group, ethoxy group, methoxymethyl group, ethoxymethyl group And an organic group having an ethyl group such as a methoxyethyl group and an ethoxyethyl group.
The compound represented by the formula (X) is not particularly limited, and examples thereof include the following.
Trivinyl isocyanurate, tri (1-propenyl) isocyanurate, triallyl isocyanurate, trimethallyl isocyanurate, methyl diallyl isocyanurate, ethyl diallyl isocyanurate, diethyl allyl isocyanurate, diethyl vinyl isocyanurate, tri (propargyl) isocyanurate , Tris (2-acryloxymethyl) isocyanurate, tris (2-acryloxyethyl) isocyanurate, tris (2-methacryloxymethyl) isocyanurate, tris (2-methacryloxyethyl) isocyanurate, ε-caprolactone-modified Tris -(2-acryloxyethyl) isocyanurate, among which triallyl isocyanurate, trimethallyl isocyanurate, tris (2-acryloxy) Ethyl) isocyanurate, tris (2-methacryloxyethyl) isocyanurate and ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate are preferred, and triallyl isocyanurate and tris (2-acryloxyethyl) isocyanurate are It is particularly preferable because the effect of improving the cycle characteristics is large. These may be used alone or in combination of two or more.

  The content of the compound represented by the formula (X) in the non-aqueous electrolyte is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.2% by mass or more. Further, it is preferably used in a content of 5% by mass or less, more preferably in a content of 3% by mass or less, and most preferably in a content of 2% by mass or less. By using the content in the above range, the effect of improving the high-temperature storage characteristics and the cycle characteristics can be sufficiently obtained, and an unnecessary increase in resistance can be suppressed.

[1-3-7. Difluorophosphate)
The difluorophosphate is not particularly limited, but examples include the following.
For example, lithium difluorophosphate, sodium difluorophosphate, potassium difluorophosphate, ammonium difluorophosphate, and the like can be mentioned, and among them, lithium difluorophosphate is particularly preferable because it has a large effect of improving cycle characteristics. These may be used alone or in combination of two or more.

  The content of the difluorophosphate in the non-aqueous electrolyte is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.2% by mass or more. Further, it is preferably used at a content of 3% by mass or less, more preferably at a content of 2% by mass or less, and most preferably at a content of 1.5% by mass or less. By using the content in the above range, the effect of improving the high-temperature storage characteristics and the cycle characteristics can be sufficiently obtained, and unnecessary gas generation can be suppressed.

[1-3-8. Dicarboxylic acid ester)
Although there is no restriction | limiting in particular as a dicarboxylic acid ester, The following are mentioned as an example.
Malonic esters and derivatives thereof, succinic esters and derivatives thereof, adipic esters and derivatives thereof, fumaric esters and derivatives thereof, maleic esters and derivatives thereof, phthalic esters and derivatives thereof, terephthalic esters and derivatives thereof.
The malonic esters and derivatives thereof include the following.
Dimethyl malonate, diethyl malonate, diethyl methyl malonate, diethyl ethyl malonate, diethyl butyl malonate, divinyl malonate, diallyl malonate, dipropargyl malonate.
The following are mentioned as a succinic ester and its derivative (s).
Dimethyl succinate, diethyl succinate, diethyl methyl succinate, diethyl dimethyl succinate, diethyl tetramethyl succinate, divinyl succinate, diallyl succinate, dipropargyl succinate.
The following are mentioned as an adipic acid ester and its derivative (s).
Dimethyl adipate, diethyl adipate, diethyl methyl adipate, diethyl dimethyl adipate, diethyl tetramethyl adipate, divinyl adipate, diallyl adipate, dipropargyl adipate.
The fumaric acid esters and derivatives thereof include the following.
Dimethyl fumarate, diethyl fumarate, diethyl methyl fumarate.
The following are mentioned as a maleic acid ester and its derivative (s).
Dimethyl maleate, diethyl maleate, diethyl methyl maleate.
The following are mentioned as a phthalic acid ester and its derivative (s).
Dimethyl phthalate, diethyl phthalate, di-2-ethylhexyl phthalate.
The following are mentioned as a terephthalic acid ester and its derivative (s).
Dimethyl terephthalate, diethyl terephthalate, di-2-ethylhexyl terephthalate.
Of these, diethyl methylmalonate, diethylethylmalonate, and diethylbutylmalonate are particularly preferred because of their high temperature storage property improving effect. These may be used alone or in combination of two or more.

  The content of the dicarboxylic acid ester in the non-aqueous electrolyte is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.5% by mass or more. Further, it is preferably used at a content of 5% by mass or less, more preferably at a content of 4% by mass or less, and most preferably at a content of 3% by mass or less. By using the content in the above range, the effect of improving the high-temperature storage characteristics can be sufficiently obtained, and unnecessary deterioration of the cycle characteristics can be suppressed.

[1-4. Electrolytes〕
The electrolyte used for the non-aqueous electrolyte of the present invention is not limited, and any known electrolyte can be used as long as it is used as an electrolyte in the intended non-aqueous electrolyte secondary battery. When the non-aqueous electrolyte of the present invention is used for a lithium secondary battery, a lithium salt is usually used as an electrolyte.

Specific examples of the electrolyte include inorganic lithium salts such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiSO ₃ F, and LiN (FSO ₂ ) ₂ ;
LiCF ₃ SO ₃ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,3-hexafluoropropane disulfonylimide, lithium cyclic 1,2-tetrafluoroethane _{disulfonylimide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2), LiC (CF 3 SO 2) 3, LiPF 4 (CF 3) 2, LiPF 4 (C _{2 F 5) 2, LiPF 4} (CF 3 SO 2) 2, LiPF 4 (C 2 F 5 SO 2) 2, LiBF 2 (CF 3) 2, LiBF 2 (C 2 F 5) 2, LiBF 2 (CF Fluorinated organic lithium salts such as ₃ SO ₂ ) ₂ and LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ;
Examples thereof include lithium salts of dicarboxylic acid complexes such as lithium bis (oxalato) borate, lithium difluorooxalatoborate, lithium tris (oxalato) phosphate, lithium difluorobis (oxalato) phosphate, and lithium tetrafluoro (oxalato) phosphate.

Among these, LiPF ₆ , LiBF ₄ , LiSO ₃ F, LiN (FSO ₂ ) ₂ , and LiN (FSO ₂ ) (LiSO ₄ ) from the viewpoint of solubility and dissociation degree in non-aqueous solvent, electric conductivity and obtained battery characteristics. CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium bis (oxalato) borate, lithium difluorooxalatoborate, lithium tris (oxalato) phosphate, lithium difluorobis ( Oxalato) phosphate and lithium tetrafluoro (oxalato) phosphate are preferred, and LiPF ₆ and LiBF ₄ are particularly preferred.

In addition, one kind of the electrolyte may be used alone, or two or more kinds may be used in any combination and in any ratio. Above all, when two kinds of specific inorganic lithium salts are used in combination or an inorganic lithium salt and a fluorine-containing organic lithium salt are used in combination, gas generation during trickle charging is suppressed, and deterioration after high-temperature storage is suppressed. This is preferred. In particular, the combination and the LiPF ₆ and LiBF _4, and an inorganic lithium salt such as _{LiPF 6, LiBF 4, LiCF 3} SO 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) _2, etc. It is preferable to use together with a fluorine-containing organic lithium salt.

Further, when LiPF ₆ and LiBF ₄ are used in combination, it is preferable that LiBF ₄ be contained in a proportion of usually 0.01% by mass or more and 50% by mass or less based on the whole electrolyte. The ratio is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, while preferably 20% by mass or less, more preferably 10% by mass or less, particularly preferably 5% by mass or less, Most preferably, it is at most 3% by mass. When the ratio is in the above range, a desired effect can be easily obtained, and the increase in the resistance of the electrolytic solution due to the low dissociation degree of LiBF ₄ can be suppressed.

On the other hand, inorganic lithium salts such as LiPF ₆ and LiBF ₄ , inorganic lithium salts such as LiSO ₃ F and LiN (FSO ₂ ) ₂ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ and LiN (C ₂ F) ₅ SO _{2) 2,} lithium cyclic 1,3-hexafluoropropane disulfonylimide, lithium cyclic 1,2-tetrafluoroethane _{disulfonylimide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2), LiC ( CF ₃ SO ₂ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₂ ( Fluorinated organic lithium salts such as CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ , and lithium bis (oxalato) Borate, lithium tri When used in combination with a lithium salt of a dicarboxylic acid complex such as (oxalato) phosphate, lithium difluorooxalatoborate, lithium tri (oxalato) phosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluoro (oxalato) phosphate, the entire electrolyte is used. Is usually 70% by mass or more, preferably 80% by mass or more, more preferably 85% by mass or more, and usually 99% by mass or less, preferably 95% by mass or less.

  The concentration of the lithium salt in the non-aqueous electrolytic solution of the present invention is arbitrary as long as the gist of the present invention is not impaired, but is usually 0.5 mol / L or more, preferably 0.6 mol / L or more, more preferably 0.1 mol / L or more. 8 mol / L or more. In addition, the range is usually 3 mol / L or less, preferably 2 mol / L or less, more preferably 1.8 mol / L or less, and still more preferably 1.6 mol / L or less. When the concentration of the lithium salt is in the above range, the electric conductivity of the non-aqueous electrolytic solution becomes sufficient, and the electric conductivity decreases due to the increase in viscosity, and the non-aqueous electrolytic solution using the non-aqueous electrolytic solution of the present invention. A decrease in the performance of the secondary battery is suppressed.

[1-5. Non-aqueous solvent)
The non-aqueous solvent contained in the non-aqueous electrolyte of the present invention can be appropriately selected from those conventionally known as solvents for non-aqueous electrolytes.
Examples of commonly used non-aqueous solvents include cyclic carbonate, chain carbonate, chain and cyclic carboxylic acid ester, chain and cyclic ether, phosphorus-containing organic solvent, sulfur-containing organic solvent, aromatic fluorinated solvent and the like. No.

  Examples of the cyclic carbonate include cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate, and the carbon number of the cyclic carbonate is usually 3 or more and 6 or less. Among them, ethylene carbonate and propylene carbonate are preferable in that the electrolyte is easily dissolved due to high dielectric constant, and the cycle characteristics are good when used in a non-aqueous electrolyte secondary battery.

  Examples of the chain carbonate include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and chain carbonates such as di-n-propyl carbonate. The number of carbon atoms is preferably 1 or more and 5 or less, particularly preferably 1 or more and 4 or less. Among them, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable from the viewpoint of improving battery characteristics. Further, chain carbonates in which a part of hydrogen of an alkyl group is substituted with fluorine are also included. Examples of the chain carbonate substituted with fluorine include bis (fluoromethyl) carbonate, bis (difluoromethyl) carbonate, bis (trifluoromethyl) carbonate, bis (2-fluoroethyl) carbonate, and bis (2,2-difluoroethyl) Examples thereof include carbonate, bis (2,2,2-trifluoroethyl) carbonate, 2-fluoroethylmethyl carbonate, 2,2-difluoroethylmethyl carbonate, and 2,2,2-trifluoroethylmethyl carbonate.

Examples of the chain carboxylic acid ester include methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and propionic acid. Isopropyl, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, methyl valerate, ethyl valerate, methyl pivalate, ethyl pivalate, etc., and chains in which hydrogen has been partially substituted with fluorine for these compounds Carboxylic acid esters. Examples of the chain carboxylic acid ester substituted with fluorine include methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and 2,2,2-trifluoroethyl trifluoroacetate. Among them, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, methyl isobutyrate, ethyl isobutyrate, and methyl pivalate are batteries. It is preferable from the viewpoint of improving characteristics.
Examples of the cyclic carboxylate include γ-butyrolactone, γ-valerolactone, and the like, and cyclic carboxylate in which a part of hydrogen of these compounds is substituted with fluorine. Among these, γ-butyrolactone is more preferred.

As the chain ether, dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxymethane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1 -Ethoxymethoxyethane, 1,2-ethoxymethoxyethane, and the like, and chain ethers obtained by substituting a part of hydrogen of these compounds with fluorine. As a chain ether substituted with fluorine, bis (trifluoroethoxy) ethane, ethoxytrifluoroethoxyethane, methoxytrifluoroethoxyethane, 1,1,1,2,2,3,4,5,5,5-deca Fluoro-3-methoxy-4-trifluoromethyl-pentane, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-ethoxy-4-trifluoromethyl-pentane, 1 , 1,1,2,2,3,4,5,5,5-decafluoro-3-propoxy-4-trifluoromethyl-pentane, 1,1,2,2-tetrafluoroethyl-2,2 Examples include 3,3-tetrafluoropropyl ether, 2,2-difluoroethyl-2,2,3,3-tetrafluoropropyl ether, and the like. Among these, 1,2-dimethoxyethane and 1,2-diethoxyethane are more preferred.
Examples of the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, and the like, and cyclic ethers in which a part of hydrogen of these compounds is substituted with fluorine.

  Examples of the phosphorus-containing organic solvent include trimethyl phosphate, triethyl phosphate, dimethylethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethylene ethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, Examples include triphenyl phosphite, trimethyl phosphine oxide, triethyl phosphine oxide, triphenyl phosphine oxide, and the like, and phosphorus-containing organic solvents in which a part of hydrogen of these compounds is substituted with fluorine. Examples of the phosphorus-containing organic solvent substituted with fluorine include tris (2,2,2-trifluoroethyl) phosphate and tris (2,2,3,3,3-pentafluoropropyl) phosphate.

  Examples of the sulfur-containing organic solvent include sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethylsulfone, diethylsulfone, ethylmethylsulfone, methylpropylsulfone, dimethylsulfoxide, methyl methanesulfonate, ethyl methanesulfonate, and methyl ethanesulfonate , Ethyl ethanesulfonate, dimethyl sulfate, diethyl sulfate, dibutyl sulfate, and the like, and sulfur-containing organic solvents obtained by substituting a part of hydrogen of these compounds with fluorine.

  Examples of the aromatic fluorinated solvent include fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, benzotrifluoride and the like.

  Among the above non-aqueous solvents, it is preferable to use ethylene carbonate and / or propylene carbonate, which are cyclic carbonates. Further, when these are used in combination with a chain carbonate, both high conductivity and low viscosity of the electrolytic solution can be achieved. Is preferred.

  One type of non-aqueous solvent may be used alone, or two or more types may be used in combination in any combination and in any ratio. When two or more kinds are used in combination, for example, when a cyclic carbonate and a chain carbonate are used in combination, a suitable content of the chain carbonate in the nonaqueous solvent is usually 20% by volume or more, preferably 40% by volume or more. Further, it is usually 95% by volume or less, preferably 90% by volume or less. On the other hand, a suitable content of the cyclic carbonate in the nonaqueous solvent is usually 5% by volume or more, preferably 10% by volume or more, and usually 80% by volume or less, preferably 60% by volume or less. When the proportion of the chain carbonate is in the above range, the increase in the viscosity of the non-aqueous electrolyte is suppressed, and the decrease in the electrical conductivity of the non-aqueous electrolyte due to the decrease in the degree of dissociation of the lithium salt as the electrolyte is suppressed. In the present specification, the volume of the nonaqueous solvent is a value measured at 25 ° C., but for a solid such as ethylene carbonate at 25 ° C., the value measured at the melting point is used.

[1-5. Other additives)
The non-aqueous electrolyte solution of the present invention may contain various additives as long as the effects of the present invention are not significantly impaired. As the additive, conventionally known additives can be arbitrarily used. One type of additive may be used alone, or two or more types may be used in any combination and in any ratio.

(Overcharge prevention agent)
Specific examples of the overcharge inhibitor include alkylbiphenyls such as 2-methylbiphenyl and 2-ethylbiphenyl, terphenyl, partially hydrogenated terphenyls, cyclopentylbenzene, cis-1-propyl-4-phenylcyclohexane, trans -1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, diphenyl ether, dibenzofuran, ethylphenyl carbonate, tris (2-t-amylphenyl) phosphate , Tris (3-t-amylphenyl) phosphate, tris (4-t-amylphenyl) phosphate, tris (2-cyclohexylphenyl) phosphate, tris (3-cyclohexylphenyl) phosphate, tris (4-cyclohexyl) Aromatic compounds such as (silphenyl) phosphate, triphenylphosphate, tolylphosphate, tri (t-butylphenyl) phosphate, methylphenylcarbonate and diphenylcarbonate; 2-fluorobiphenyl, 3-fluorobiphenyl, 4-fluorobiphenyl, Partially fluorinated aromatic compounds such as 4'-difluorobiphenyl, 2,4-difluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoroanisole, Fluorine-containing anisole compounds such as 6-difluoroanisole and 3,5-difluoroanisole.

  The content of these overcharge inhibitors in the non-aqueous electrolyte is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.5% by mass or more. It is at least 5 mass%, preferably at most 5 mass%, preferably at most 3 mass%, more preferably at most 2 mass%. When the concentration is in the above range, the desired effect of the overcharge preventing agent is easily exerted, and the deterioration of battery characteristics such as high-temperature storage characteristics is suppressed. By including an overcharge inhibitor in the non-aqueous electrolyte, the rupture of the non-aqueous electrolyte secondary battery due to overcharge can be suppressed, and the stability of the non-aqueous electrolyte secondary battery is preferably improved.

  Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate, methoxyethyl-ethyl carbonate, ethoxyethyl-methyl carbonate, and ethoxyethyl-ethyl carbonate; Spiro compounds such as 1,8,10-tetraoxaspiro [5.5] undecane and 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; 1-methyl-2-pyrrolidinone , 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, N-methylsuccinimide and other nitrogen-containing compounds; heptane, octane, nonane, decane, cyclohexane Heptane, methylcyclohexane, ethylcyclohexane Hydrocarbon compounds such as propylcyclohexane, n-butylcyclohexane, t-butylcyclohexane, and dicyclohexyl; methyldimethylphosphinate, ethyldimethylphosphinate, ethyldiethylphosphinate, trimethylphosphonoformate, triethylphosphonoformate, trimethylphosphono Acetate, triethylphosphonoacetate, phosphorus-containing compounds such as trimethyl-3-phosphonopropionate, triethyl-3-phosphonopropionate, succinic anhydride, methyl succinic anhydride, 4,4-dimethyl succinic anhydride, 4,5-dimethyl succinic anhydride, maleic anhydride, citraconic anhydride, dimethyl maleic anhydride, phenyl maleic anhydride, diphenyl maleic anhydride, phthalic anhydride, cyclohexane 1,2-dica Bon acid anhydride, acetic anhydride, propionic anhydride, acrylic anhydride include acid anhydride such as methacrylic acid. Of these, succinic anhydride, maleic anhydride, and methacrylic anhydride are preferred from the viewpoint of improving cycle characteristics and high-temperature storage characteristics. These may be used alone or in combination of two or more.

  The content of these auxiliaries in the non-aqueous electrolyte is not particularly limited, but is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more. It is usually at most 8% by mass, preferably at most 5% by mass, more preferably at most 3% by mass, further preferably at most 2% by mass. The addition of these auxiliaries is preferable in that the capacity retention characteristics after high-temperature storage and the cycle characteristics are improved. When the concentration is in the above range, the effect of the auxiliary agent is easily exerted, and the deterioration of battery characteristics such as high-rate discharge characteristics is suppressed.

[2. Negative electrode)
The negative electrode active material used for the negative electrode will be described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples include a carbonaceous material, an alloy-based material, and a lithium-containing metal composite oxide material. These may be used alone or in any combination of two or more.

<Negative electrode active material>
Examples of the negative electrode active material include a carbonaceous material, an alloy-based material, and a lithium-containing metal composite oxide material.

  Examples of the carbonaceous material include (1) natural graphite, (2) artificial graphite, (3) amorphous carbon, (4) carbon-coated graphite, (5) graphite-coated graphite, and (6) resin-coated graphite. .

  (1) Examples of the natural graphite include flaky graphite, flaky graphite, soil graphite, and / or graphite particles obtained by subjecting these graphites to raw materials such as spheroidization and densification. Among these, spherical or ellipsoidal graphite that has been subjected to a spheroidizing treatment is particularly preferable from the viewpoint of the filling properties of the particles and the charge / discharge rate characteristics.

  As an apparatus used for the spheroidizing treatment, for example, an apparatus that repeatedly applies mechanical action such as compression, friction, and shearing force including particle interaction mainly to impact force to particles can be used. Specifically, the casing has a rotor with a number of blades installed inside, and the rotor rotates at a high speed, so that mechanical action such as impact compression, friction, and shearing force is applied to the carbon material introduced therein. And a device for performing a sphering treatment is preferable. Further, it is preferable to have a mechanism for repeatedly giving a mechanical action by circulating the carbon material.

  (2) As artificial graphite, coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbon, nitrogen-containing cyclic compound, sulfur-containing cyclic compound, polyphenylene, polyvinyl chloride, Organic compounds such as polyvinyl alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin are usually in the range of 2500 ° C. or higher and usually 3200 ° C. or lower. Examples thereof include those manufactured by graphitization at a temperature, and pulverized and / or classified as necessary. At this time, a silicon-containing compound or a boron-containing compound can be used as a graphitization catalyst. Another example is artificial graphite obtained by graphitizing mesocarbon microbeads separated during the pitch heat treatment process. Further, artificial graphite as granulated particles composed of primary particles is also included. For example, by mixing a graphitizable carbonaceous material powder such as mesocarbon microbeads or coke with a graphitizable binder such as tar and pitch and a graphitizing catalyst, graphitizing, and pulverizing as necessary. Examples of the obtained graphite particles include a plurality of obtained flat particles, which are aggregated or bonded so that their alignment planes are non-parallel.

  (3) As the amorphous carbon, amorphous carbon obtained by using a graphitizable carbon precursor such as tar or pitch as a raw material and heat-treating at least once in a non-graphitizable temperature range (range of 400 to 2200 ° C.) Examples include amorphous carbon particles that have been heat-treated using particles or a non-graphitizable carbon precursor such as a resin as a raw material.

  (4) The carbon-coated graphite can be obtained by mixing natural graphite and / or artificial graphite with a carbon precursor that is an organic compound such as tar, pitch or resin, and subjecting the mixture to a heat treatment at least once in the range of 400 to 2300 ° C. A carbon graphite composite in which natural graphite and / or artificial graphite is used as core graphite, and amorphous carbon covers the core graphite. The form of the composite may cover the entire surface or a part of the surface, or may be a composite of a plurality of primary particles using the carbon derived from the carbon precursor as a binder. In addition, natural graphite and / or artificial graphite are reacted at high temperature with hydrocarbon gases such as benzene, toluene, methane, propane, and aromatic volatiles to deposit carbon on the graphite surface (CVD). A graphite composite can also be obtained.

  (5) As the graphite-coated graphite, natural graphite and / or artificial graphite, and a carbon precursor of an easily graphitizable organic compound such as tar, pitch or resin are mixed, and once mixed at a temperature of about 2400 to 3200 ° C. Natural graphite and / or artificial graphite obtained by the above heat treatment is used as nuclear graphite, and graphite-coated graphite in which the graphitized material covers the whole or a part of the surface of the nuclear graphite is exemplified.

  (6) As the resin-coated graphite, natural graphite and / or artificial graphite is mixed with resin and the like, and the natural graphite and / or artificial graphite obtained by drying at a temperature of less than 400 ° C. is used as core graphite, and the resin and the like are used as core graphite. And resin-coated graphite coating.

  As the carbonaceous materials (1) to (6), one type may be used alone, or two or more types may be used in any combination and in any ratio.

  Examples of the organic compounds such as tar, pitch, and resin used in the above (2) to (5) include coal-based heavy oil, DC-based heavy oil, cracked petroleum heavy oil, aromatic hydrocarbon, and N-ring compound. , An S-ring compound, polyphenylene, an organic synthetic polymer, a natural polymer, a carbonizable organic compound selected from the group consisting of a thermoplastic resin and a thermosetting resin. Further, the raw material organic compound may be used by dissolving it in a low molecular weight organic solvent in order to adjust the viscosity at the time of mixing.

  Further, as natural graphite and / or artificial graphite which is a raw material of nuclear graphite, natural graphite subjected to spheroidizing treatment is preferable.

  As the alloy-based material used as the negative electrode active material, as long as it can occlude and release lithium, simple lithium, a simple metal and an alloy forming a lithium alloy, or an oxide, carbide, nitride, silicide, sulfide, or the like thereof Or a compound such as a phosphide, and is not particularly limited. The elemental metal or alloy forming the lithium alloy is preferably a material containing a metal or metalloid element of group 13 and 14 (that is, excluding carbon), more preferably an elemental metal of aluminum, silicon and tin and An alloy or a compound containing these atoms. One of these may be used alone, or two or more may be used in any combination and in any ratio.

<Physical properties of carbonaceous materials>
When a carbonaceous material is used as the negative electrode active material, the material preferably has the following physical properties.

(X-ray parameters)
The d value (interlayer distance) of the lattice plane (002 plane) of the carbonaceous material obtained by X-ray diffraction according to the Gakushin method is usually 0.335 nm or more, usually 0.360 nm or less, and 0.350 nm. Or less, more preferably 0.345 nm or less. The crystallite size (Lc) of the carbonaceous material determined by X-ray diffraction according to the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

(Volume-based average particle size)
The volume-based average particle diameter of the carbonaceous material is a volume-based average particle diameter (median diameter) determined by a laser diffraction / scattering method, and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and more preferably 7 μm. The above is particularly preferred, and usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less, and particularly preferably 25 μm or less.

  If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to an initial battery capacity loss. On the other hand, if it exceeds the above range, an uneven coating surface is likely to be formed when producing an electrode by coating, which may be undesirable in a battery manufacturing process.

  The volume-based average particle size is measured by dispersing a carbon powder in a 0.2% by mass aqueous solution (about 10 mL) of a surfactant, polyoxyethylene (20) sorbitan monolaurate, and then performing a laser diffraction / scattering type particle size distribution. (For example, LA-700 manufactured by Horiba Ltd.). The median diameter determined by the measurement is defined as the volume-based average particle diameter of the carbonaceous material of the present invention.

(Raman R value)
The Raman R value of the carbonaceous material is a value measured using a laser Raman spectrum method, and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1. 5 or less, preferably 1.2 or less, more preferably 1 or less, particularly preferably 0.5 or less.

  If the Raman R value is below the above range, the crystallinity of the particle surface becomes too high, and the number of sites where Li enters between layers may decrease with charge and discharge. That is, charge acceptability may decrease. Further, when the negative electrode is densified by pressing after being applied to the current collector, the crystals are likely to be oriented in a direction parallel to the electrode plate, which may cause a decrease in load characteristics.

  On the other hand, when the Raman R value exceeds the above range, the crystallinity of the particle surface is reduced, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be reduced and the gas generation may be increased.

The measurement of the Raman spectrum is performed by using a Raman spectrometer (for example, a Raman spectrometer manufactured by JASCO Corporation) to allow the sample to naturally fall into the measurement cell and to fill the cell, and to apply argon ion laser light (or semiconductor This is performed by rotating the cell in a plane perpendicular to the laser beam while irradiating the cell with the laser beam. The resulting Raman spectrum, the intensity I _A of the peak P _A in the vicinity of 1580 cm ^-1, and measuring the intensity I _B of a peak P _B in the vicinity of 1360 cm ^-1, the intensity ratio _{R (R = I B / I} A) Is calculated. The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material of the present invention.

The above Raman measurement conditions are as follows.
・ Laser wavelength: Ar ion laser 514.5 nm (semiconductor laser 532 nm)
- Measuring range: 1100cm ^-1 ~1730cm ^-1
Raman R value: background processing,
・ Smoothing processing: Simple average, convolution 5 points

(BET specific surface area)
BET specific surface area of the carbonaceous material is a value of the measured specific surface area using the BET method is usually 0.1 m ² · g ^-1 or more, 0.7 m ² · g ^-1 or more, 1. 0 m ² · g ^-1 or more, and particularly preferably 1.5 m ² · g ^-1 or more, generally not more than 100 m ² · g ^-1, preferably 25 m ² · g ^-1 or less, 15 m ² · g ^-1 or less is more preferable, and 10 m ² · g ^-1 or less is particularly preferable.

  When the value of the BET specific surface area falls below this range, the lithium acceptability at the time of charging when used as a negative electrode material is likely to be poor, lithium is likely to precipitate on the electrode surface, and the stability may be reduced. On the other hand, if it exceeds this range, when used as a negative electrode material, the reactivity with a non-aqueous electrolytic solution increases, gas generation tends to increase, and a preferable battery may not be obtained.

  The measurement of the specific surface area by the BET method is performed by preliminarily drying the sample at 350 ° C. for 15 minutes under a nitrogen flow using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken), and then measuring the atmospheric pressure. Using a nitrogen helium mixed gas precisely adjusted so that the value of the relative pressure of nitrogen becomes 0.3, the nitrogen adsorption BET one-point method by a gas flow method is used.

<Structure of negative electrode and fabrication method>
Any known method can be used for manufacturing the electrode as long as the effects of the present invention are not significantly impaired. For example, to form a slurry by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, and the like to the negative electrode active material, applying the slurry to a current collector, drying, and then pressing the slurry. Can be.

  When an alloy-based material is used, a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a method such as a vapor deposition method, a sputtering method, and a plating method is also used.

(Electrode density)
Although the electrode structure when the negative electrode active material is formed into an electrode is not particularly limited, the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more, and more preferably 1.2 g · cm ⁻³ or more. but more preferably, particularly preferably 1.3 g · cm ^-3 or more, preferably 2.2 g · cm ^-3 or less, more preferably 2.1 g · cm ^-3 or less, 2.0 g · cm ^-3 or less More preferred is 1.9 g · cm ^-3 or less. When the density of the negative electrode active material existing on the current collector exceeds the above range, the negative electrode active material particles are destroyed, the initial irreversible capacity increases, and the non-aqueous system near the current collector / negative electrode active material interface increases. In some cases, the charge / discharge characteristics of the high current density deteriorate due to the decrease in the permeability of the electrolyte. If the ratio is below the above range, the conductivity between the negative electrode active materials may decrease, the battery resistance may increase, and the capacity per unit volume may decrease.

[3. Positive electrode)
<Positive electrode active material>
Hereinafter, the positive electrode active material (lithium transition metal-based compound) used for the positive electrode will be described.

<Lithium transition metal compound>
The lithium transition metal compound is a compound having a structure capable of desorbing and inserting Li ions, and examples thereof include a sulfide, a phosphate compound, and a lithium transition metal composite oxide. The sulfide, and compounds having a two-dimensional layered structure, such as TiS ₂ and MoS _2, strong (in Me which various transition metals including Pb, Ag, and Cu) general formula Me _x Mo ₆ S ₈ represented by And the like, and a schurel compound having a three-dimensional skeleton structure. Examples of the phosphate compound include those belonging to an olivine structure, and are generally represented by LiMePO ₄ (Me is at least one or more transition metals). Specifically, LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , LiMnPO _{4 and the} like. Examples of the lithium transition metal composite oxide include those belonging to a spinel structure capable of three-dimensional diffusion and a layered structure capable of two-dimensional diffusion of lithium ions. Those having a spinel structure are generally represented as LiMe ₂ O ₄ (Me is at least one transition metal), and specifically, LiMn ₂ O ₄ , LiCoMnO ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiCoVO ₄ And the like. Those having a layered structure are generally represented as LiMeO ₂ (Me is at least one or more transition metals). LiCoO _{2 Specifically, LiNiO 2, LiNi 1-x} Co x O 2, LiNi 1-xy Co x Mn y O 2, LiNi 0.5 Mn 0.5 O 2, Li 1.2 Cr 0.4 Mn 0.4 O 2, Li 1.2 Cr 0.4 Ti _0.4 O ₂ , LiMnO _{2, and the} like.

(composition)
The lithium-containing transition metal compound is, for example, a lithium transition metal-based compound represented by the following composition formula (A) or (B).

1) In the case of a lithium transition metal compound represented by the following composition formula (A): Li _{1 + x} MO ₂ (A)
However, x is usually 0 or more and 0.5 or less. M is an element composed of Ni and Mn or Ni, Mn and Co, and the Mn / Ni molar ratio is usually 0.1 or more and 5 or less. The Ni / M molar ratio is usually 0 or more and 0.5 or less. The Co / M molar ratio is usually 0 or more and 0.5 or less. It should be noted that the rich portion of Li represented by x may be replaced with a transition metal site M.

  In the composition formula (A), the atomic ratio of the amount of oxygen is described as 2 for convenience, but there may be some non-stoichiometry. Further, x in the above composition formula is a charged composition in the production stage of the lithium transition metal based compound. Normally, batteries on the market are aged after the batteries are assembled. Therefore, the amount of Li in the positive electrode may be deficient with charge and discharge. In that case, x in the case of discharging to 3 V may be measured to be -0.65 or more and 1 or less in composition analysis.

  Further, the lithium transition metal-based compound obtained by firing at a high temperature in an oxygen-containing gas atmosphere in order to enhance the crystallinity of the positive electrode active material has excellent battery characteristics.

Further, the lithium transition metal-based compound represented by the composition formula (A) may be a solid solution with Li ₂ MO ₃ called a 213 layer as shown in the following general formula (A ′).
αLi ₂ MO ₃ · (1-α) LiM'O ₂ (A ')

In the general formula, α is a number satisfying 0 <α <1.
M is at least one metal element having an average oxidation number of 4 ⁺ , and specifically, is at least one metal element selected from the group consisting of Mn, Zr, Ti, Ru, Re, and Pt.

M ′ is at least one metal element having an average oxidation number of 3 ⁺ , preferably at least one metal element selected from the group consisting of V, Mn, Fe, Co and Ni, more preferably , Mn, Co, and Ni.

2) If a lithium transition metal-based compound represented by the following general formula _{(B) Li [Li a M} b Mn 2-ba] O 4+ δ ··· (B)
Here, M is an element composed of at least one of transition metals selected from Ni, Cr, Fe, Co, Cu, Zr, Al and Mg.

The value of b is usually 0.4 or more and 0.6 or less.
When the value of b is within this range, the energy density per unit weight of the lithium transition metal-based compound is high.

  The value of a is usually 0 or more and 0.3 or less. In addition, a in the above composition formula is a charged composition in a production stage of the lithium transition metal-based compound. Normally, batteries on the market are aged after the batteries are assembled. Therefore, the amount of Li in the positive electrode may be deficient with charge and discharge. In that case, a in the case of discharging to 3 V may be measured to be -0.65 or more and 1 or less in composition analysis.

  When the value of a is within this range, the energy density per unit weight of the lithium transition metal compound is not significantly impaired, and good load characteristics can be obtained.

Further, the value of δ is usually in the range of ± 0.5.
When the value of δ is in this range, the stability as a crystal structure is high, and the cycle characteristics and high-temperature storage of a battery having an electrode manufactured using this lithium transition metal-based compound are good.

  Here, the chemical meaning of the lithium composition in the lithium-nickel-manganese-based composite oxide, which is the composition of the lithium transition metal-based compound, will be described in more detail below.

  In order to obtain a and b in the composition formula of the lithium transition metal-based compound, each transition metal and lithium are analyzed by an inductively coupled plasma emission spectrometer (ICP-AES) to obtain a ratio of Li / Ni / Mn. It is calculated by

  From a structural point of view, it is considered that the lithium related to a is substituted into the same transition metal site. Here, the average valence of M and manganese becomes larger than 3.5 due to the charge neutrality principle due to lithium according to a.

Further, the lithium transition metal based compound may be substituted with fluorine, LiMn ₂ O ₄ - is denoted as _x F _2x.

(blend)
Specific examples of the lithium transition metal compound having the above composition include, for example, Li _{1 + x} Ni _0.5 Mn _0.5 O ₂ , Li _{1 + x} Ni _0.85 Co _0.10 Al _0.05 O ₂ , and Li _{1 + x} Ni _0.33 Mn _0.33 Co _Examples include _0.33 O ₂ , Li _{1 + x} Ni _0.45 Mn _0.45 Co _0.1 O ₂ , Li _{1 + x} Mn _1.8 Al _0.2 O ₄ , and Li _{1 + x} Mn _1.5 Ni _0.5 O ₄ . These lithium transition metal-based compounds may be used alone or in a combination of two or more.

(Introduction of different elements)
Further, a foreign element may be introduced into the lithium transition metal-based compound. As the different elements, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Ru, Rh, Pd, Ag, In, Sb, Te , Ba, Ta, Mo, W, Re, Os, Ir, Pt, Au, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi , N, F, S, Cl, Br, I, As, Ge, P, Pb, Sb, Si and Sn. These foreign elements may be incorporated in the crystal structure of the lithium transition metal compound, or may not be incorporated in the crystal structure of the lithium transition metal compound, and may be included alone or in the compound on the particle surface or crystal grain boundary. May be unevenly distributed.

<Configuration and manufacturing method of positive electrode for lithium secondary battery>
The positive electrode for a lithium secondary battery is obtained by forming a positive electrode active material layer containing the above-described lithium transition metal-based compound powder for a lithium secondary battery positive electrode material and a binder on a current collector.
The positive electrode active material layer is usually formed by mixing a positive electrode material, a binder, and, if necessary, a conductive material and a thickener, etc. in a dry manner into a sheet and pressing the sheet to the positive electrode current collector. Alternatively, these materials are dissolved or dispersed in a liquid medium to form a slurry, and the slurry is applied to the positive electrode current collector and dried.

  As the material of the positive electrode current collector, a metal material such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and a carbon material such as carbon cloth and carbon paper are usually used. In the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punched metal, a foamed metal, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder And the like. Note that the thin film may be appropriately formed in a mesh shape.

  When a thin film is used as the positive electrode current collector, its thickness is arbitrary, but is preferably in the range of usually 1 μm or more and 100 mm or less. If the thickness is smaller than the above range, the strength required as a current collector may be insufficient, while if the thickness is larger than the above range, handleability may be impaired.

  The binder used for producing the positive electrode active material layer is not particularly limited, and in the case of a coating method, any material may be used as long as the material is stable to a liquid medium used for producing the electrode. Resin-based polymers such as polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitrocellulose, SBR (styrene / butadiene rubber), NBR (acrylonitrile / butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene Rubbery polymers such as propylene rubber, styrene / butadiene / styrene block copolymers and hydrogenated products thereof, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / ethylene copolymer, Styrene / isoprene styrene bronze Elastomeric polymers such as copolymers and their hydrogenated products, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer, etc. Ion conductivity of soft resinous polymers, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polymers such as fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, and alkali metal ions (particularly lithium ions) And the like. One of these substances may be used alone, or two or more of them may be used in any combination and in any ratio.

  The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 80% by mass or less. When the ratio of the binder is too low, the mechanical strength of the positive electrode is insufficient because the positive electrode active material cannot be sufficiently held, and there is a possibility that the battery performance such as cycle characteristics may be deteriorated. It may lead to a decrease in battery capacity and conductivity.

  The positive electrode active material layer usually contains a conductive material to increase conductivity. The type is not particularly limited, but specific examples include metal materials such as copper and nickel, graphite (graphite) such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. And the like. One of these substances may be used alone, or two or more of them may be used in any combination and in any ratio. The proportion of the conductive material in the positive electrode active material layer is usually 0.01% by mass or more and 50% by mass or less. If the proportion of the conductive material is too low, the conductivity may be insufficient, while if it is too high, the battery capacity may be reduced.

  As a liquid medium for forming a slurry, it is possible to dissolve or disperse a lithium transition metal-based compound powder as a positive electrode material, a binder, and a conductive material and a thickener used as necessary. The type of the solvent is not particularly limited, and either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water, alcohols, and the like. Examples of organic solvents include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran (THF), toluene, acetone, dimethylether, dimethylacetamide, hexamethylphosphalamide, dimethylsulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like. be able to. In particular, when an aqueous solvent is used, a dispersant is added in addition to the thickener, and a slurry is formed using a latex such as SBR. One of these solvents may be used alone, or two or more thereof may be used in an optional combination and ratio.

  The content ratio of the lithium transition metal-based compound powder as the positive electrode material in the positive electrode active material layer is usually 10% by mass or more and 99.9% by mass or less. If the ratio of the lithium transition metal-based compound powder in the positive electrode active material layer is too large, the strength of the positive electrode tends to be insufficient, and if it is too small, the capacity may be insufficient.

The thickness of the positive electrode active material layer is usually about 10 to 200 μm.
The electrode density of the positive electrode after pressing is usually 2.2 g / cm ³ or more and 4.2 g / cm ³ or less.

  The positive electrode active material layer obtained by coating and drying is preferably compacted by a roller press or the like in order to increase the packing density of the positive electrode active material.

[4. (Separator)
Usually, a separator is interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the non-aqueous electrolyte of the present invention is usually used by impregnating the separator.

  The material and shape of the separator are not particularly limited, and any known materials can be used as long as the effects of the present invention are not significantly impaired. Among them, a resin, a glass fiber, an inorganic material, or the like, which is formed of a material that is stable with respect to the nonaqueous electrolytic solution of the present invention, is used, and a porous sheet or a nonwoven fabric-like material having excellent liquid retention properties is used. Is preferred.

  As a material of the resin and the glass fiber separator, for example, polyolefin such as polyethylene and polypropylene, aromatic polyamide, polytetrafluoroethylene, polyether sulfone, a glass filter and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. One of these materials may be used alone, or two or more thereof may be used in any combination and in any ratio.

  The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. If the separator is too thin than the above range, the insulation and the mechanical strength may decrease. On the other hand, if the thickness is more than the above range, not only may the battery performance such as rate characteristics decrease, but also the energy density of the whole non-aqueous electrolyte secondary battery may decrease.

  Further, when a porous material such as a porous sheet or a nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Further, it is usually at most 90%, preferably at most 85%, more preferably at most 75%. If the porosity is less than the above range, the film resistance tends to increase and the rate characteristics tend to deteriorate. On the other hand, if it is too large, the mechanical strength of the separator tends to decrease, and the insulating property tends to decrease.

  The average pore diameter of the separator is also arbitrary, but is usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If the average pore diameter exceeds the above range, a short circuit is likely to occur. On the other hand, if the ratio is below the above range, the film resistance may increase and the rate characteristics may decrease.

  On the other hand, examples of the inorganic material include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate. Used.

  As the form, a thin film such as a nonwoven fabric, a woven fabric, or a microporous film is used. In the case of a thin film, those having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above independent thin film shape, a separator obtained by forming a composite porous layer containing the above inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder may be used. For example, a porous layer may be formed on both surfaces of the positive electrode using alumina particles having a 90% particle size of less than 1 μm and a fluorocarbon resin as a binder.

  The characteristics of the separator in the non-electrolyte secondary battery can be grasped by the Gurley value. The Gurley value indicates the difficulty in passing air in the thickness direction of the film, and is represented by the number of seconds required for 100 ml of air to pass through the film. Means it is harder to get through. That is, a smaller value means better communication in the thickness direction of the film, and a larger value means poor communication in the thickness direction of the film. The continuity is the degree of connection of the holes in the film thickness direction. If the Gurley value of the separator of the present invention is low, it can be used for various applications. For example, when used as a separator for a non-aqueous lithium secondary battery, a low Gurley value means easy movement of lithium ions, and is preferable because of excellent battery performance. The Gurley value of the separator is optional, but is preferably 10 to 1000 seconds / 100 ml, more preferably 15 to 800 seconds / 100 ml, and still more preferably 20 to 500 seconds / 100 ml. When the Gurley value is 1000 seconds / 100 ml or less, the electric resistance is substantially low, and the separator is preferable.

[5. Battery design)
<Electrode group>
The electrode group has a stacked structure in which the positive electrode plate and the negative electrode plate are interposed with the separator interposed therebetween, and a structure in which the positive electrode plate and the negative electrode plate are spirally wound with the separator interposed therebetween. Either may be used. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy) is usually 40% or more, preferably 50% or more, and usually 90% or less, and preferably 80% or less. .

  If the electrode group occupancy is below the above range, the battery capacity will decrease. In addition, when the above range is exceeded, the void space is small, and when the temperature of the battery becomes high, the member expands or the vapor pressure of the liquid component of the electrolyte becomes high, so that the internal pressure rises, and the charge / discharge repetition performance of the battery becomes high. In some cases, a gas release valve that lowers various characteristics such as high temperature and high-temperature storage, and further releases internal pressure to the outside may be operated.

<Outer case>
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the nonaqueous electrolyte used. Specifically, a metal such as a nickel-plated steel plate, stainless steel, aluminum or an aluminum alloy, a magnesium alloy, or a laminated film (laminated film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, a metal of aluminum or an aluminum alloy or a laminated film is suitably used.

  In an outer case using metals, a metal is welded to each other by laser welding, resistance welding, ultrasonic welding to form a sealed hermetic structure, or a caulking structure using the above metals via a resin gasket. Things. An outer case using the above-mentioned laminated film includes a case in which a resin layer is heat-sealed to form a sealed structure. In order to enhance the sealing property, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a hermetically sealed structure, the metal and the resin are joined, so that a resin having a polar group or a polar group introduced as an intervening resin is used. Resins are preferably used.

<Protective element>
As a protection element, PTC (Positive Temperature Coefficient) which increases resistance when abnormal heat or excessive current flows, temperature fuse, thermistor, interrupts current flowing to the circuit due to sudden rise in battery internal pressure or internal temperature during abnormal heat generation (A current cutoff valve) or the like can be used. It is preferable to select a protection element that does not operate under normal use of a high current, and it is more preferable that the protection element be designed not to cause abnormal heat generation or thermal runaway without the protection element.

<Outer body>
The non-aqueous electrolyte secondary battery of the present invention is generally constituted by housing the above-mentioned non-aqueous electrolyte, negative electrode, positive electrode, separator and the like in an outer package. This exterior body is not particularly limited, and any known exterior body can be adopted as long as the effects of the present invention are not significantly impaired. Specifically, the material of the exterior body is arbitrary, but usually, for example, nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, or the like is used.

  The shape of the exterior body is also arbitrary, and may be, for example, any of a cylindrical shape, a square shape, a laminate type, a coin shape, and a large size.

<Battery voltage>
The non-aqueous electrolyte secondary battery of the present invention is usually used at a battery voltage of 4.3 V or more. Preferably, the battery voltage is 4.3 V or higher, more preferably 4.35 V or higher, and most preferably 4.4 V or higher. This is because increasing the battery voltage can increase the energy density of the battery. On the other hand, when the battery voltage is increased, the potential of the positive electrode increases, which causes a problem that side reactions on the positive electrode surface increase. By using the electrolyte solution and the battery of the present invention, the above problem can be solved. However, if the voltage is too high, the amount of side reaction on the positive electrode surface becomes too large, and the battery characteristics deteriorate. Therefore, the upper limit of the battery voltage is preferably 5 V or less, more preferably 4.8 V or less, and most preferably 4.6 V or less.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded.

<Preparation of non-aqueous electrolyte>
<Example 1-1>
In a dry argon atmosphere, ethylene carbonate (hereinafter, referred to as EC), ethyl methyl carbonate (hereinafter, referred to as EMC), and diethyl carbonate (hereinafter, referred to as DEC) were mixed at 30% by volume, 40% by volume, and 30% by volume, respectively. LiPF ₆ was dissolved in a water solvent to a concentration of 1.2 M, and 2% by mass of vinylene carbonate and 2% by mass of fluoroethylene carbonate were added. Further, 0.3% by mass of Compound 2-10 was added to prepare a non-aqueous electrolyte.

<Comparative Example 1-1>
A non-aqueous electrolyte solution was prepared in the same manner as in Example 1-1, except that the non-aqueous electrolyte solution containing no compound 2-10 was used in the non-aqueous electrolyte solution of Example 1-1.

<Comparative Example 1-2>
Example 1 Except that 0.3% by mass of a compound A (not included in the present invention) represented by the following formula was added to the nonaqueous electrolyte solution of Example 1-1 in place of compound 2-10. In the same manner as in -1, a non-aqueous electrolyte solution was prepared.

<Preparation of negative electrode>
To 98 parts by mass of graphite powder as a negative electrode active material, 1 part by mass of an aqueous dispersion of sodium carboxymethyl cellulose and 1 part by mass of an aqueous dispersion of styrene-butadiene rubber were added as a thickener and a binder, respectively, and mixed with a disperser. To make a slurry. The obtained slurry was applied to one surface of a copper foil, dried and pressed to form a negative electrode. The prepared negative electrode was dried under reduced pressure at 60 ° C. for 12 hours and used.

<Preparation of positive electrode>
1.6 parts by mass of a conductive additive and 1.6 parts by mass of a binder (pVDF) were added to 96.8 parts by mass of lithium cobalt oxide as a positive electrode active material, and mixed with a disperser to form a slurry. The obtained slurry was applied to both sides of an aluminum foil, dried and pressed to prepare a positive electrode. The produced positive electrode was dried under reduced pressure at 80 ° C. for 12 hours and used.

<Preparation of battery>
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminated film in which both surfaces of aluminum (40 μm in thickness) are covered with a resin layer while projecting positive and negative terminals, the non-aqueous electrolyte solution of each example or comparative example was obtained. Was poured into a bag, and vacuum sealing was performed to produce a sheet-like battery. Further, in order to enhance the adhesion between the electrodes, the sheet-shaped battery was sandwiched between glass plates and pressed.

<Characteristic evaluation test>
Test 1. 60 ° C. High Temperature Storage Test Each of the batteries prepared as described above was charged at 25 ° C. to 4.4 V, discharged to 3 V, and conditioned until the capacity was stabilized. Thereafter, the battery charged to 4.4 V was left in an environment of 60 ° C. for 10 days. At this time, the remaining capacity ratio (%) was measured. The capacity at the time of discharging to 3 V at 0.2 C at 25 ° C. after the test is defined as the remaining capacity, and the ratio of the remaining capacity to the capacity before the test is defined as the remaining capacity ratio.

  As is clear from Table 1, the use of the electrolytic solution of the present invention significantly improved the residual capacity ratio as in Example 1-1. On the other hand, when the electrolytic solution containing the compound A, which is not the electrolytic solution of the present invention, was used, the residual capacity ratio was improved, but the improvement effect was not obtained as much as when the electrolytic solution of the present invention was used.

<Example 2-1>
In a dry argon atmosphere, ethylene carbonate (hereinafter, referred to as EC), ethyl methyl carbonate (hereinafter, referred to as EMC), and diethyl carbonate (hereinafter, referred to as DEC) were mixed at 30% by volume, 40% by volume, and 30% by volume, respectively. LiPF ₆ was dissolved to 1.2 M in a water solvent, and 2% by mass of vinylene carbonate, 2% by mass of fluoroethylene carbonate and 1% by mass of adiponitrile were added. Further, 0.3% by mass of Compound 2-10 was added to prepare a non-aqueous electrolyte. A sheet-shaped battery was produced in the same manner as in Example 1-1 except that this non-aqueous electrolyte was used.

<Comparative Example 2-1>
A non-aqueous electrolyte was prepared in the same manner as in Example 2-1 except that a non-aqueous electrolyte containing no compound 2-10 was used in the non-aqueous electrolyte of Example 2-1. A sheet-like battery was produced in the same manner as in Example 2-1 except that this non-aqueous electrolyte was used.

Test 2. Cycle Test The battery prepared as described above was charged at 25 ° C. to 4.4 V, discharged to 3 V, and conditioned until the capacity was stabilized. Thereafter, a cycle test in which the battery was charged to 4.4 V and discharged to 3 V in an environment of 45 ° C. was repeated 500 cycles at a current value of 0.7 C. (1C indicates a current value that takes one hour to charge or discharge). The ratio of the discharge capacity at the 200th cycle to the discharge capacity at the first cycle was defined as a 200-cycle capacity retention rate (%). The ratio of the discharge capacity at the 500th cycle to the discharge capacity at the first cycle was defined as a 500-cycle capacity retention rate (%).

  As is clear from Table 2, the use of the electrolytic solution of the present invention has the effect of improving the cycle capacity retention rate.

<Example 3-1>
In a dry argon atmosphere, ethylene carbonate (hereinafter, referred to as EC), ethyl methyl carbonate (hereinafter, referred to as EMC), and diethyl carbonate (hereinafter, referred to as DEC) were mixed at 30% by volume, 40% by volume, and 30% by volume, respectively. LiPF ₆ was dissolved to 1.2 M in a water solvent, and 2% by mass of vinylene carbonate, 2% by mass of fluoroethylene carbonate and 1% by mass of adiponitrile were added. Further, 0.3% by mass of Compound 2-10 was added to prepare a non-aqueous electrolyte. A sheet-shaped battery was produced in the same manner as in Example 1-1 except that this non-aqueous electrolyte was used.

<Example 3-2>
A non-aqueous electrolyte was prepared in the same manner as in Example 3-1 except that the content of compound 2-10 was changed to 0.5% by mass in the non-aqueous electrolyte of Example 3-1. A sheet-shaped battery was produced in the same manner as in Example 3-1 except that this non-aqueous electrolyte was used.

<Comparative Example 3-1>
A non-aqueous electrolyte was prepared in the same manner as in Example 3-1 except that a non-aqueous electrolyte containing no compound 2-10 was used in the non-aqueous electrolyte of Example 3-1. A sheet-shaped battery was produced in the same manner as in Example 3-1 except that this non-aqueous electrolyte was used.

<Comparative Example 3-2>
In the same manner as in Example 3-1 except that 0.3% by mass of the compound A used in Comparative Example 1-2 was added to the non-aqueous electrolyte solution of Example 3-1 instead of the compound 2-10. A non-aqueous electrolyte was prepared. A sheet-shaped battery was produced in the same manner as in Example 3-1 except that this non-aqueous electrolyte was used.

Test 3. 80 ° C. High Temperature Storage Test The battery prepared as described above was charged to 4.4 V at 25 ° C., discharged to 3 V, and conditioned until the capacity was stabilized. Thereafter, the battery charged to 4.4 V was left under an environment of 80 ° C. for 3 days. At this time, the gas generation rate (%) and the remaining capacity rate (%) were measured. In addition, the gas generation rate is obtained by calculating the amount of gas generated during the test using the Archimedes method, and is defined as a ratio (%) when the gas amount of Comparative Example 3-1 is set to 100 (the smaller the numerical value, the better). Further, the capacity at the time of discharging to 3 V at 0.2 C at 25 ° C. after the test is defined as the remaining capacity, and the ratio of the remaining capacity to the capacity before the test is defined as the remaining capacity ratio.

  As is clear from Table 3, the use of the electrolytic solution of the present invention provided an effect of reducing the gas generation rate, and also confirmed an effect of improving the remaining capacity ratio. On the other hand, in Comparative Example 3-2 using an electrolyte solution not according to the present invention, although a similar improvement effect was observed, it did not reach the electrolytic solution according to the present invention.

<Example 4-1>
In a dry argon atmosphere, ethylene carbonate (hereinafter, referred to as EC), ethyl methyl carbonate (hereinafter, referred to as EMC), and diethyl carbonate (hereinafter, referred to as DEC) were mixed at 30% by volume, 40% by volume, and 30% by volume, respectively. LiPF ₆ was dissolved in a water solvent to have a concentration of 1.2 M, and 2% by mass of vinylene carbonate and 2% by mass of fluoroethylene carbonate were added. Further, 0.3% by mass of Compound 2-10 was added to prepare a non-aqueous electrolyte. A sheet-shaped battery was produced in the same manner as in Example 1-1 except that this non-aqueous electrolyte was used.

<Example 4-2> A non-aqueous electrolyte solution was prepared in the same manner as in Example 4-1 except that the compound 2-10 was replaced with the compound 3-2 in the non-aqueous electrolyte solution of the example 4-1. Prepared. A sheet-shaped battery was produced in the same manner as in Example 4-1 except that this non-aqueous electrolyte was used.

<Comparative Example 4-1>
A non-aqueous electrolyte was prepared in the same manner as in Example 4-1 except that the non-aqueous electrolyte containing no compound 2-10 was used in the non-aqueous electrolyte of Example 4-1. A sheet-shaped battery was produced in the same manner as in Example 4-1 except that this non-aqueous electrolyte was used.

<Comparative Example 4-2>
A non-aqueous electrolyte was prepared in the same manner as in Example 4-1 except that the compound B (not included in the present invention) was used instead of the compound 2-10 in the non-aqueous electrolyte of Example 4-1. did. A sheet-shaped battery was produced in the same manner as in Example 4-1 except that this non-aqueous electrolyte was used.

<Comparative Example 4-3>
A non-aqueous electrolyte was prepared in the same manner as in Example 4-1 except that the compound C (not included in the present invention) was used instead of the compound 2-10 in the non-aqueous electrolyte of Example 4-1. did. A sheet-shaped battery was produced in the same manner as in Example 4-1 except that this non-aqueous electrolyte was used.

<Comparative Example 4-4>
A non-aqueous electrolyte solution was prepared in the same manner as in Example 4-1 except that the compound D (not included in the present invention) was used instead of the compound 2-10 in the non-aqueous electrolyte solution of Example 4-1. did. A sheet-shaped battery was produced in the same manner as in Example 4-1 except that this non-aqueous electrolyte was used.

<Comparative Example 4-5>
A non-aqueous electrolyte was prepared in the same manner as in Example 4-1 except that the compound A (not included in the present invention) was used instead of the compound 2-10 in the non-aqueous electrolyte of Example 4-1. did. A sheet-shaped battery was produced in the same manner as in Example 4-1 except that this non-aqueous electrolyte was used.

Test 4.85 ° C. High Temperature Storage Test The battery prepared as described above was charged at 25 ° C. to 4.4 V, discharged to 3 V, and conditioned until the capacity was stabilized. Thereafter, the battery charged to 4.4 V was left in an environment of 85 ° C. for 6 hours. The gas generation rate (%) at this time was measured. In addition, the gas generation rate is obtained by calculating the amount of gas generated during the test using the Archimedes method, and is defined as a ratio (%) when the gas amount of Comparative Example 4-1 is set to 100 (the smaller the numerical value, the better).

Test 5. Load Discharge Test The battery prepared as described above was charged to 4.4 V at 25 ° C., discharged to 3 V, and conditioned until the capacity was stabilized. Thereafter, the battery charged to 4.4 V was discharged to 3 V at a current of 0.2 C in an environment of 25 ° C. (the capacity at this time is referred to as a 0.2 C capacity). Again, the battery charged to 4.4 V was discharged to 3 V at a current of 0.5 C under an environment of 25 ° C. (the capacity at this time was set to 0.5 C capacity). At this time, a value of 0.5 C capacity / 0.2 C capacity × 100 (%) was obtained as a load characteristic.

  As is clear from Table 4, in Example 4-1 and Example 4-2 using the electrolytic solution of the present invention, the gas generation rate was significantly suppressed and the load characteristics were improved as compared with Comparative Example 4-1. It was possible. On the other hand, in Comparative Example 4-2, Comparative Example 4-4, and Comparative Example 4-5 using maleimide, which is not the electrolytic solution of the present invention, the load characteristics were maintained or improved as compared with Comparative Example 4-1. However, the gas generation rate increased greatly. Similarly, Comparative Example 4-3 using maleimide which was not the electrolytic solution of the present invention had a lower gas generation rate than Comparative Example 4-1. It got worse. From these results, it can be said that it is necessary to use the specific compound of the present invention in order to simultaneously suppress the gas generation and improve the load characteristics.

  According to the non-aqueous electrolyte solution of the present invention, the decomposition of the electrolyte solution of the non-aqueous electrolyte secondary battery is suppressed, gas generation is suppressed when the battery is used in a high temperature environment, and the remaining capacity of the battery is improved. In both cases, it is possible to manufacture a non-aqueous electrolyte secondary battery having improved cycle characteristics and excellent discharge load characteristics (high-rate discharge is possible) and a high energy density. Therefore, it can be suitably used in various fields such as electronic devices using a non-aqueous electrolyte secondary battery.

  The use of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited, and can be used for various known uses. Specific examples include notebook computers, pen input computers, mobile computers, e-book players, mobile phones, mobile faxes, mobile copies, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, and transceivers. , Electronic organizer, calculator, memory card, portable tape recorder, radio, backup power supply, motor, car, motorcycle, motorbike, bicycle, lighting equipment, toy, game equipment, clock, power tool, strobe, camera, large home Examples include a storage battery and a lithium ion capacitor.

Claims (7)

A non-aqueous electrolyte used for a secondary battery, comprising a positive electrode having a positive electrode active material capable of occluding and releasing metal ions and a negative electrode having a negative electrode active material capable of occluding and releasing metal ions. A non-aqueous electrolyte solution containing a compound represented by the following formula (2) or a compound represented by the following formula (3) .

(In the formula (2), R ^{17 to} R ²⁶ are each independently any one of a group represented by a hydrogen atom, a halogen atom, a hydrocarbon group, -OL ¹ , and -SO ₂ -L ² L ¹ and L ² are charcoal
Shows a hydride group. At least three of R ^{17 to} R ²⁴ represent groups other than a hydrogen atom. )

(In the formula (3), R ^{27 to} R ⁴⁴ are each independently any one of a group represented by a hydrogen atom, a halogen atom, a hydrocarbon group, —OL ¹ , and —SO ₂ —L ² L ¹ and L ² are charcoal
Shows a hydride group. ) The total content of the compound represented by the formula (2) or the compound represented by the formula (3) is 0.01% by mass or more and 5% by mass or less in the non-aqueous electrolyte. The non-aqueous electrolyte according to claim 1. In the compound represented by the formula (2) , R ^{17 to} R ²⁴ are a hydrogen atom or an alkyl group , and in the compound represented by the formula (3), R ^{27 to} R ⁴² are a hydrogen atom or an alkyl group . The non-aqueous electrolyte according to claim 1 or 2 , wherein: The non-aqueous electrolyte according to any one of claims 1 to 3 , wherein the amount of water in the non-aqueous electrolyte is 40 mass ppm or less. The non-aqueous electrolyte solution according to any one of claims 1 to 4 , further comprising at least one of a cyclic carbonate having a carbon-carbon unsaturated bond and a cyclic carbonate having a fluorine atom. The non-aqueous electrolyte according to any one of claims 1 to 5 , further comprising a nitrile compound. A positive electrode having a positive electrode active material capable of occluding and releasing metal ions, a negative electrode having a negative electrode active material capable of occluding and releasing metal ions, and a nonaqueous electrolyte secondary battery including a nonaqueous electrolyte. A non-aqueous electrolyte secondary battery using the non-aqueous electrolyte described in any one of Items 1 to 6 .